• Journal of the Korea Institute of Building Construction
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• v.24 no.2
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• pp.169-180
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• 2024

In this study, to suggest an efficient method of using coal gasification slag(CGS), a byproduct from integrated gasification combined cycle(IGCC), as a combined fine aggregate for concrete mixture, the diverse performances of concrete mixtures with combined fine aggregates of CGS, river sand, and crushed sand were evaluated. Additionally, using CGS, the reduction of the hydration heat and the strength developing performance were analyzed to provide a method for reducing the heat of hydration of mass concrete by using combined fine aggregate with CGS and replacing fly ash with cement. The results of the study can be summarized as follows: as a method of recycling CGS from IGCC as concrete fine aggregate, a combination of CGS with crushed sand offers advantages for the concrete mixture. Additionally, when the CGS combined aggregate is used with low-heat-mix designed concrete with fly ash, it has the synergistic effect of reducing the hydration heat of mass concrete compared to the low-heat-designed concrete mixture currently in wide use.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2002.03a
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• pp.159-168
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• 2002

A recently developed filbert-Huang transform (HHT) technique is applied to detect damage locations of bridge structures. The HHT may be used to identify the locations of damages which exhibit nonlinear and nonstationary behavior, since the HHT can show the instantaneous frequency characteristics of the signal. A series of numerical simulations were conducted for bridge pier systems with damages under a controlled load with sweeping frequency. The results of the numerical simulation study indicate that the HHT method can reasonably identify damage locations using a limited number of acceleration sensors under severe measurement noise condition.

• Journal of Korean Society of Transportation
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• v.16 no.1
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• pp.7-24
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• 1998

1960년대 이후 경제규명의 괄목할 만한 성장과 생산규모가 확대되어 비용 최소화를 통한 물류분 야의 근대화가 핵심적인 문제로 대두됨에도 불구하고 체계적이며 효율적인 물류체계의 부재로 인한 물 류비의 상승은 산업경쟁력을 약화시켜 물가상승등의 경제불안을 초래하고 있다. 또 가중되는 도시내 교 통혼잡과 최근들어 시행되고 잇는 도시내 화물차량에 대한 각종 규제로 물류비중 수송비의 비증은 지속 적으로 증가되고 있는 실정이다. 이에 따라 사회적으로 물류비를 절감시킬수 있는 물류시설에 관한 관 심이 고조되고 있으며 국가나 지방자치 단체 차원에서도 지역간의 물류거점으로서의 유통단지나 복합화 물터미널 등에 대한 필요성이 강조되고 있는 실정이다. 그러나 이러한 지역간 물류거점으로서 체계뿐만 아니라 도시내에서의 물류활동 즉 도시내에 위치한 최종소비자를 대상으로한 수·배송은 도시교통문제 와 물류서비스를 최종적으로 실행과 직결되어 있다는 점에서 매우 중요한 의미를 갖는다. 따라서 본연 구에서는 도시내 물류거점 시설인 배송센타를 대상으로 배송센타 1일 가동시 총물류비용 모형을 도출하 여 1일 총물류비용을 최소화 할 수 있는 배송센터 최적수 결정 모의 실험 모형을 구성하였다. 이와 병 행하여 최근 들어 대형화물차량에 대한 도심진입규제 통행제한 등 각종 화물차량 규제로 인하여 배송행 태 변화에 따른 사례를 상정하여 민간 차원에서 규제후 변화된 물류비의 변화정도와 그비용을 감소시킬 수 있는 방안의 검토를 시행하였다.

• Journal of KIISE:Information Networking
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• v.36 no.1
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• pp.43-49
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• 2009

The Mobile IPv6(MIPv6) has a well-known time gap of packet loss between link down and binding update. To minimize such packet loss, this paper proposes a MIPv6-based dual tunneling mechanism, which keeps exploiting the old tunnel while creating a new tunnel. Superiority of the proposed mechanism is evaluated by quantitative analysis on the lost packets and computer simulation, based on two overlay heterogeneous access networks, such as the UMTS and a WLAN.

• Journal of the Earthquake Engineering Society of Korea
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• v.7 no.4
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• pp.89-95
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• 2003

In this paper, an algorithm to locate and size damage in a complex truss structure using the time domain response is presented. Sampled response data for specific time interval is spatially expanded over the structure to obtain the mean train energy for each element of the structure. The mean strain energy for each element is, in turn, used to build a damage index that represents the ratio of the stiffness parameter of the pre-damaged to the post-damaged structure. The validity of the methodology is demonstrated using data from a numerical example of a space truss structure with simulated damage. Also in the example, the effects of noisy data on the proposed algorithm are examined by adding random noised to the response data.

• Proceedings of the Korea Water Resources Association Conference
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• 2019.05a
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• pp.343-343
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• 2019

일반적으로 지역홍수빈도해석은 두가지 목적을 내포하고 있다. 첫 번째는 자료기간이 짧은 지점에 대하여 지역빈도해석을 통하여 보다 신뢰성있는 홍수빈도를 추정하기 위한 것이며, 두 번째는 지역화를 통한 미계측지점에서의 홍수빈도를 추정하기 위한 것이다. 자료샘플의 확충을 통한 신뢰성있는 홍수빈도를 추정하기 위한 연구는 국내에서도 활발히 연구가 진행되었으나. 미계측지점에서의 홍수빈도를 추정하기 위한 연구는 관측홍수량 자료 및 지점수의 부재로 미미한 실정이다. 또한, 지역화를 통한 미계측지점에서의 홍수빈도를 추정하기 위해 지역홍수빈도분석을 수행할 수 있는 관측홍수량 자료가 확보되었을 경우라 하더라도, 공간적으로 추가적인 지점의 자료가 확보될 경우, 지역화 결과의 민감도에 대한 연구는 전혀 이루어지지 못하고 있다. 따라서, 본 연구에서는 충주댐 상류유역의 22개 지점에 대한 모의홍수량 자료를 기반으로, 무작위로 분석지점을 선택하여 그에 따른 홍수빈도의 지역화 결과에 대한 변화를 고찰하고자 하였다. 이는 분석 유역의 지역홍수빈도분석을 수행하기에 적합한 홍수자료의 공간정보에 대한 의미를 정략적으로 파악할 수 있을 것으로 판단된다.

• Journal of the Korea Concrete Institute
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• v.15 no.1
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• pp.87-94
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• 2003

Construction plan and strength control have limitations in construction production field because it is difficult to predict the form removal strength and development of specified concrete strength. However, we can have reasonable construction plan and strength control if prediction of concrete strength is available. In this study, firstly, the newly proposed strength prediction model with maturity method was compared with the logistic model to test the adaptability. Secondly, the determination of time of form removal was verified through the new strength prediction model. As the results, it is found that investigation of the activation energy that are used to calculate equivalent age is necessary, and new strength prediction model was proved to be more accurate in the strength prediction than logistic model in the early age. Moreover, the use of new model was more reasonable because it has low SSE and high decisive factor. If we adopt new strength prediction model at construction field, we can expect the reduced period of work through the reduced time of form removal.

• Journal of Korean Society of Environmental Engineers
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• v.35 no.11
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• pp.785-794
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• 2013

Combined sewer overflows during rainfall events contain sewer sediments and surface pollutants. This can cause significant chemical, physical and biological problems to receiving watershed. However, there are no method that can commonly apply to decide criteria for controlling the pollutant load. In this study, it sets up the reduction goals of combined sewer overflow through long-term simulation using the rainfall-runoff model. From a review of domestic and foreign management standard of combined sewer overflow for this, it makes decision that 60% (phase 1), 85% (phase 2) of total pollutant load and frequency per year for reduction goals is more proper. Also, the result of analyzing long-term simulation (minimum 10 years) applied to research basin indicates that reduction goals of BOD pollutant load are 1,123 kg (phase 1) and 2,374 kg (phase 2), and overflow volumes for research objective achievement are $11,685m^3$ (phase 1) and $24,701m^3$ (phase 2).

• Journal of the Korea Concrete Institute
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• v.18 no.5 s.95
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• pp.631-637
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• 2006

In this study, fundamental properties such as fresh and hardened performance of concrete mix(specification : 25-24-18) added fluorine-silicate hybrid based crack reducing agent(FS) were measured. Addition of FS ranged from 0.5% to 2.0% at intervals 0.5% based on cement weight. Adequate dosage(0.5%) of FS derived from basic properties measurements applied and compared resistance for shrinkage crack. The permeability of concrete in the absence(24-S-0.0) and presence(24-S-0.5) of evaluated at a mock-up sized concrete. Concrete added FS improved resistance for shrinkage crack and consequently crack number, length and area decreased to $50{\sim}74.4%$ compared non-added. As well, by the addition of FS, the resistance for permeability and penetration depth to concrete surface region increased 67% and 40%, respectively. Therefore it was confirmed that shrinkage crack resistance and permeability of concrete could be improved by the addition of FS.

• Journal of the Korean Association of Geographic Information Studies
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• v.14 no.2
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• pp.96-108
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• 2011

Going abreast of high public concerns on the environment, the need of environmental modeling has been increased to assess the impact of space exploitation of environment. GIS offers potential solutions to the many problems encountered during water-quality modeling. But there are also many problems associated with the modeling. The preparation of necessary parameters for the modeling can be complicated. Also, the results from one model can be different from each other even the same area is analyzed. This paper aims to develop the data processing system to couple the Qual2E and HyGIS in which Qual2E input and output data files can be created, modified and processed using HyGIS and assess the performance of the system. A structural analysis and standardization of modeling are conducted to identify data flow and processing of Qual2E. Algorithms of the defined processors are designed and developed as component modules. The data model of HyGIS-Qual2E is designed, and GUI(Graphical User Interface) is developed using Visual Basic 6.0 and GDK.