• Journal of Korea Water Resources Association
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• v.41 no.2
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• pp.163-172
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• 2008

Hydrologic regimes play a major role in determining the biotic composition, structure, and function of river ecosystem. In this study, hydrologic regimes were analyzed on down stream effects of the Young-Chun dam construction using the Indicators of Hydrologic Alterations(IHA). The analysis results were as follows ; (1) Monthly mean flows were decreased during drought and flood season on the pre and post dam, (2) Magnitude and Duration of Annual Exterm Conditions, annual minima 1-day means was $3.48m^3/sec$, $0.89m^3/sec$ and annual maxima 1-day mean was $833.1m^3/sec$, $672.1m^3/sec$ on the pre and post dam (3) Timing of Annual Exterm conditions, Julian date of the annual minima 1-day means was 180th(June) in the pre dam, 257th(September) in the post dam, Julian date of the annual maxima 1-day means was 209th(July) in the pre dam, 217th(August) in the post dam, (4) Frequency and Duration of High and Low Pulse, Low Puls counts and duration were 3 times and 23 days in the pre dam, High Pulse counts and duration were 4 times and 2 days in the pre dam. (5) Rate and Frequency of Water Condition Changes, rise rates was 39.27 %, 19.36 % and fall rates -15.85 %, -8.16 % in the pre and post dam, respectively (6) Coefficient of Variation, annual exteram water conditions were decreased from 0.9054 to 0.6314 and from 1.0440 to 0.9617, Timing of Annual Exterm conditions were incereased for minima flow from 0.269 to 0.282, for maxima form 0.069 to 0.153.

• Advances in concrete construction
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• v.14 no.1
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• pp.71-77
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• 2022

Creep phenomenon affects the stability and integrity of concrete structures. An inaccurate prediction of these strains may lead to the appearance of cracks and excessive deflections which may cause in some cases the demolition of structures. In fact, the measured values of these uncontrolled strains appear often to be clearly different and larger than the expected ones. Therefore, an accurate prediction of concrete deformations is a necessity. As a matter of fact, the codified descriptions of this phenomenon are unreliable and don't consider the effect of admixtures. The physical nature of creep is not well understood and almost all creep models are mainly of empirical nature. To overcome this issue, a study of the correlation between different parameters affecting concrete creep is performed and a new model for predicting creep of concrete is elaborated. This new model considers the effect of admixtures, specifically the silica fume, in predicting concrete creep and allows an accurate prediction of this phenomenon. The proposed model is based on the observation of physical behavior of creep phenomenon. It targets at expressing creep compliance in terms of structural and environmental parameters. In fact, the experimental observations show that creep curves follow two kinetic regimes leading to a model called Phenomenological Creep Model. By adequate regressions and substitutions, and according to this model, we can express creep compliance in terms of structural, environmental parameters and admixture types and percentage. The proposed new Phenomenological Creep Model Silica Fume (PCM19SF) calculates accurately creep of concrete by considering the effect of silica fume.

• Proceedings of KOSOMES biannual meeting
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• 2008.05a
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• pp.5-10
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• 2008

In recent years, the major interest in international environmental laws has focused on the ways to secure observation of the laws. For the implementation and compliance of international marine environmental convention, the new sequence of developing convention has been sdopted. The main convention is adopted in a form of 'Framework Convention' and the details are expressed in the Annex and/or Guidelines of the convention for the purpose of conveniense of adoption and to secure the observation of the convention And the Annexes or Guidelines are amended, revised and newly adopted continuously. Therefore this study is to analyze the tendency of sequence for developing new convention, which will help understanding one particular international marine environmental convention as a whole.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.03a
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• pp.963-971
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• 2008

Unsaturated soil mechanics has been often used to find out a cause of failure (tensile failure) of retaining walls and hill slopes containing sandy soils. Checking shear strength is a popular method by considering suction stress developed form pore water menisci among the grains and saturated pockets of pore water under negative pressure. Linear Mohr-Coulomb failure criterion is generally adopted as a failure criterion. However, depending on relative density, stress history, and the magnitude of stress, the failure behavior of sand may not follow linear M-C frictional behavior. For stress in the large compressive ranges, say from tens to hundreds of kPa, the linear M-C criterion is an adequate representation for the shear strength behavior of sand. However, less than tens of kPa, the M-C criterion often can not be accurately represented. Depending on failure criterion, the uniaxial tensile strength is different over 100% relative error. For sand behavior under small compression regimes, therefore, such as under low or zero gravity, or under undergoing tensile failure in the crest area of hill slopes or behind retaining walls, it is important to consider the non-linear behavior.

• Journal of Korean Society on Water Environment
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• v.33 no.1
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• pp.51-62
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• 2017

The purpose of this study is to evaluate on the applicability of Load Duration Curve (LDC) method using Maintenance of Variance Extension types 2 method and sampling data for efficient total maximum daily loads at the Nakbon-A unit watershed in Korea. The LDC method allows for characterizing water quality data such as BOD, TOC, T-N and T-P in this study at different flow regimes(or quarters). BOD usually exceeded the standard value (exceedance probability 50%) at low flow zone. On the other hand, TOC, T-N, T-P usually exceeded the standard value at dry and low flow zone. Seasonally all water quality variables usually exceeded the standard value at Q1(Jan-Mar) and Q2(Apr-Jun) zones. Improvement of effluent control from wastewater treatment plants are effective to improve BOD and T-P.

• Journal of Korean Society of Environmental Engineers
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• v.35 no.4
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• pp.294-300
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• 2013

In this study, major parameter of partial nitritation was investigated for the stable operation. In order to establish partial nitritation system, prevailing parameters such as temperature, BA (bicarbonate alkalinity) and pH were evaluated. As a result, it is inferred that appropriate bicarbonate alkalinity ratio (mg $NaHCO_3{\cdot}L^{-1}/mg$ Inf. $NH_4{^+}-N{\cdot}L^{-1}$) drives stable 50% partial nitritation at $32^{\circ}C$ and ambient temperature, respectively. Alkalinity ratio was proposed as new strategy for 50% partial nitritation without pH control in both temperature regimes. Because of the results, it was added amound of BA required only for 50% nitritation to inhibit nitratation. The effluent $NO_2{^-}-N/NH_4{^+}-N$ ratio reached almost 100% when initial bicarbonate alkalinity ratios (mg $NaHCO_3{\cdot}L^{-1}/mg$ Inf. $NH_4{^+}-N{\cdot}L^{-1}$) were 6.8 (R1) and 6.7 (R2), respectively. Polymerase chain reaction and denaturing gradient gel electrophoresis (PCR-DGGE) results demonstrated that AOB was the dominant nitrifying bacteria and NOB was negligible after adopting process control.

• Journal of Korea Port Economic Association
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• v.25 no.4
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• pp.203-224
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• 2009

The purpose of this paper is to analyze the relationship between the budget allocation of Busan-Gwangyang port and political variables such as general election, presidential election, local election and political regimes. To do this, this study did correlation analyses using budget data of all ports in Korea, Busan, and Gwangyang during 1985-2007. The main results of the correlation analyses are as follow: First, there was a positive correlation between budget of Busan and local election. Also, there was a positive correlation between budget of Gwangyang and presidential election. This results suggest that public choice model and political business cycle model seem to apply to the port development policy. Second, there was no correlation between the regionalism of the political regime and budget of Busan-Gwangyang ports. Third, it can be inferred that the national agenda of the hub strategy can be positively related to the implementation of port development budget. Further studies are needed to analyse the relationship between the political variables and establishment of port plan, decision making about port development and ground-breaking of port construction.

• 한국사회정책
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• v.24 no.4
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• pp.3-29
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• 2017

The study checked whether the trade-off relationship between the home ownerhip and welfare by Kemeny and Castles was still valid in four welfare regimes, and analysed the factors of change and stability on rate of home ownership between social democratic states and southern european states. Based on the results of the study, the relationship between housing ownership and public expenditure was confirmed only in the liberal welfare regime and in the conservative welfare regime, as evidenced by the 2014 data collection. Second, social democratic states have dramatically increased housing mortgage loans and showed signs of housing commodification but southern european states have showed pre commodification of housing, maintained comparatively whole home ownership and low mortgage loans. Third, social democratic states has resulted in a rise in housing demand and housing prices, through reduced new housing and social rented housing construction, home owenership friendly taxation and generous lending policies, but southern european states have maintained a stable housing demand and housing prices thanks to the rich housing stocks, extended family, self provision and self promotion by close relatives, and intergenerational inheritance and transfers of housing. Although sequence of the equity ownership and welfare are still unclear, it is not a rational alternatives to induce housing ownership through large mortgage loans.

• Journal of Environmental Policy
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• v.6 no.2
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• pp.97-122
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• 2007

In 2006, the Ministry of Environment of the Republic of Korea, completed the construction on national environmental geographic informations including National Environmental Assessment Map, Ecological Map, Land Cover Map and so on. At this point of time, it is necessary to establish the advance strategy on national environmental geographic information, considering the complicated characteristics. Therefore, this study suggests the advance strategy on national environmental geographic information, reflecting results of analyzing the given condition and the trend of informatization. National environmental geographic information has spacial quality to be managed dispersedly in a department unit or an operations unit. According to this quality, requirements for users who need the policy based on national environmental geographic information and complex information are not satisfactory. And, the information system centering the process of administrative affairs should be converted to one putting decision supporting first in importance. Therefore, this study sets up "the realization of the sustainable land management system by advancing national environmental geographic information" as the vision of the advancing strategy. In order to accomplish the vision, this study established the purpose as follow; constructing strategic and geographic information based on knowledge, arranging the foundation to open information to the public transparently, building expanded and integrated national environmental geographic information, embodying the environmental administration based on national environmental geographic information, enhancing the efficiency of national environmental geographic information, and supporting efficiently the process of administrative affairs. And this study suggests executive plans to achieve the vision and the purpose as next; developing the quality control program to verify the information confidence, building the system to integrate and to provide environmental information, collecting information, readjusting laws and regimes in parts of the construction, the application and the management of the system, and operating the task process, human power, organization and information technology. This study puts the emphasis on providing the turning opportunity politically which is possible to make sure of the information confidence in quality, advancing from the expansion of one in quantity. However, this improvement strategy doesn't reflect all national environmental geographic information and current status of environmental administrations. Therefore, for applying the result of this study to the actual environmental administration, it is necessary to discuss regularly the systematic categorization of national environmental geographic information, to interview with the contracting parties and so on hereafter.

• Journal of the Korea Concrete Institute
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• v.18 no.3 s.93
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• pp.331-338
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• 2006

This paper presents the experimental results on volumetric changes in ordinary portland cement concrete made with various water-to-cement ratios(W/C's) ranging from 0.32 to 0.50 and cured in low different conditions. Curing regimes employed in this work were designed to exhibit autogenous and drying shrinkage as well as swelling of concrete. The concrete avoided any moist evaporation(Regime f showed only autogenous shrinkage and the lower the W/C, the feater the autogenous shrinkage. The concrete exposed to air drying conditions at $20{\pm}1^{\circ}C$ and $60{\pm}3%$ RH after 6-day water curing at $20{\pm}1^{\circ}C$(Regime II) swelled and then started to shrink. The maximum swelling value of concrete developed in water curing was between 15 and $40{\pm}10^{-6}$, and the greatest total shrinkage(autogenous+drying shrinkage) was obtained for the mixture made with W/C of 0.32. The concrete let to air drying conditions(Regime III) showed greater total shrinkage compared to the concrete cured in Regime II. The concrete exposed to air drying condition after 6-day sealed curing(Regime IV) exhibited slightly smaller total shrinkage than that of the concrete cured in Regime III. Net drying shrinkage that can be derived from the results of Regime I, III, and IV increased as the W/C increased despite of similar total shrinkage. This result indicated that drying shrinkage governs total shrinkage of high-W/C concretes. In other words, a portion of autogenous shrinkage in total shrinkage increased in low-W/C concretes. Therefore, it should be controlled in terms of cracking potential. Finally, total shrinkage of high-strength and high-performance concrete made with low W/C can be effectively reduced by appropriate early moisture curing.