• Journal of Energy Engineering
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• v.17 no.4
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• pp.182-188
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• 2008

This paper is to compare the carbon-balanced and liner air-fuel ratio determination methods for alternative fuels. In the previous work, expansion of Eltinge chart, unburned hydrocarbon compensation, comparison of the results from various methods were discussed. It has been also concluded that Eltinge method might be regarded as the most general equation of AFR determination among the existing ones. In the recent years, however, increasing demand for the environmental preservation, including global warming-up protection, and energy conservation lead to introduce the alternative fuel to the internal combustion engine. Therefore, the exact calculations of AFR for these fuels are needed. Especially, for the fuel that contains oxygen, all AFR calculation equations except Eltinge have to be re-formulated. In this paper, the AFR for alternative fuel were calculated by re-formulated carbon balance, accuracy of which was already confirmed, and linear equations, which are newly proposed by statistical method for each fuel. The results show that AFRs based on carbon balance have a little more error compared with gasoline, however, the accuracy is enough for this formula to apply to various fuel. The proposed linear equation also have excellent accuracy below $\lambda=1.2$.

• Journal of the Korean Geosynthetics Society
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• v.22 no.1
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• pp.39-51
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• 2023

The bearing capacity of the prebored pile has been studied by many researchers. However, The bearing capacity of the prebored pile has been studied by many researchers. However, comparative studies between design data and pile load test data on the load sharing ratio and the settlement were insignificant. Therefore, the design data and the static load test results were compared for the prebored open-end steel piles. In the compressive static pile load test, the load sharing ratios of the base resistance and the shaft resistance were 13%~40% and 60%~87%, respectively and the settlements were measured 2.2mm~4.7mm. In the current bearing capacity calculation formula, the base resistance was shared between 54% and 75%, and the shaft resistance was shared between 25% and 46% and the settlements were calculated about 19.8mm~23.6mm. The settlement in the current bearing capacity calculation formula was 321% to 776% (average : 445%) larger than the settlement in the result of load test. When the settlement were calculated using the load sharing ratio in the pile load tests, it was 137% to 525% larger than the test settlement, and it was as large as 204% on average. It was confirmed that an appropriate evaluation of the load sharing ratio had an important effect on the calculation of pile settlement.

• Journal of Korean Society of Transportation
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• v.21 no.3
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• pp.107-120
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• 2003

Over the decades, a lot of studies have dealt with the traffic characteristics and phenomena at a merging area. However, relatively few analytical techniques have been developed to evaluate the traffic flow at the area and, especially, the ramp merging capacity has rarely been. This study focused on the merging behaviors that were characterized by the relationship between the shoulder lane flow and the on-ramp flow, and modeled these behaviors to determine ramp merge capacity by using gap acceptance theory. In the process of building the model, both an ideal mergence and a forced mergence were considered when ramp-merging vehicles entered the gap provided by the flow of the shoulder lane. In addition, the model for the critical gap was proposed because the critical gap was the most influential factor to determine merging capacity in the developed models. The developed models showed that the merging capacity value was on the increase as the critical gap decreased and the shoulder lane volume increased. This study has a meaning of modeling the merging behaviors including the forced merging type to determine ramp merging capacity more precisely. The findings of this study would help analyze traffic phenomena and understand traffic behaviors at a merging area, and might be applicable to decide the primary parameters of on-ramp control by considering the effects of ramp merging flow.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.29 no.1B
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• pp.47-62
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• 2009

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.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.34 no.6
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• pp.1807-1814
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• 2014

Natural disaster has been hard to prevent the occurrence of itself, thus in order to reduce the economic damages and loss casualties, it is important to be prepared in cases that the disasters should occur in advance. Interest of the related project to prevent various natural disasters has been grown along with an investment in Korea. Along with this movement, when investments related to natural disaster prevention projects were built on, the post evaluation that can verify the ripple effects of those investments on the community should be emerging as an essential task. For evaluating the effects of public investment projects such as natural disaster prevention projects in this study, the related researches would continue through qualitative analyses, for example, cost-benefit analysis. Even the qualitative analysis alone cannot fully explain the effects of those projects, the diverse methods of analyzing and evaluating those effects might not have been presented in those fields. For the post evaluation of natural disaster prevention projects through the qualitative analysis, this study derived subjects that had effects on the post evaluation of natural disaster prevention projects. Also, employing the structural equation modeling (SEM), the causation between post evaluation subjects and the effects of projects were quantitatively analyzed, and the weighting factors of evaluation items were calculated respectively. Based on these results, post evaluation index formula was proposed for the natural disaster prevention projects in Korea.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.9 no.3
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• pp.143-151
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• 1989

An equation to predict the ground settlement caused by tunneling through granular soils is proposed, The equation is developed modifying the Murayama equation using the results of elastic finite element analysis. Ground settlements at the underground structures in Korea and other countries are analyzed. From the results of the settlement analysis, it is found that the ground settlement associated with tunneling through granular soils is not only affected by tunnel geometry but also related to volume change characteristics of soils. It is also found that the widths of shear band, t in field conditions are 2 to 6 times greater than the values proposed in the Murayama's model. Calculated settlements using the proposed equation show reasonable agreement with the observed settlements and the results from the elasto-plastic finite element analysis. Murayama equation seems to underestimate the ground settlement.

• Journal of Korean Society for Geospatial Information Science
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• v.24 no.3
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• pp.93-101
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• 2016

Reservoir area and reservoir capacity must be evaluated for reservoir management such a water supply, water-purity control and so on. In this paper, the reservoir area and reservoir capacity according to the level of storage range of water(149~156 El.m) could be calculated by using TIN data model of study area, Gyoyeon reservoir, TIN data model was made of DSM which was created by using UAV and GCP survey. From the results of applying the various functions to reservoir area and capacity, reservoir area and reservoir capacity according to the level of storage range of water showed the highest coefficient of determination of 0.97 in fourth-order polynomial, and 0.99 in second-order polynomial, respectively. Thus, it could be expected the efficient reservoir management by estimating reservoir area and capacity curve equation through UAV photogrammetry.

• Journal of the Korean GEO-environmental Society
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• v.7 no.3
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• pp.55-68
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• 2006

This paper studies the moment equations in the 2000 Canadian highway bridge code(CHBDC) for soil-steel box structures, which are applicable to the span less than 8m. Finite element analyses carried out for soil-steel box structures having spans of 3-12m using the deep corrugated steel plates under three construction stages; backfill up to the crown, backfill up to the cover depth, and live loading. The coefficients of moment equations are newly proposed based on the results of numerous finite element analyses considering various design variables, such as span length, soil depth, backfill conditions. The validity of the proposed coefficients in the moment equations of the 2000 CHBDC is investigated by the comparison with the existing coefficients and numerical results of finite element analyses. The comparisons show that the moments of the 2000 CHBDC give good predictions for the span less than 8m, but underestimate for the span greater than 8m, whereas the proposed moments give good estimates of numerical results for the spans of 3-12m.

• Journal of Korea Water Resources Association
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• v.47 no.6
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• pp.547-559
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• 2014

The objective of this study is to evaluate the performance of the complementary relationship-based evapotranspiration models, namely, advection-aridity (AA) model of Brutsaert and Stricker and the CRAE model of Morton for estimating actual evapotranspiration. Both models were applied to the Bokhacheon middle-upper watershed, and their estimates were evaluated against the water balance estimate. The calculation was made on a daily basis and comparison was made on monthly and annual bases. For comparison, the water balance estimates were not obtained from the observed precipitation and streamflow data but were based on the simulated data by using integrated watershed model, SWAT-K which is the revised version of SWAT. The reason not to directly use the observed data for water balance estimate is that the credible record period is not sufficient and the streamflow has been altered due to water use and release. Overall, the results showed that both AA model and CRAE model with their original parameters overestimate annual and monthly evapotranspiration, and the large difference between the complementary relationship-based approach and the water balance approach occurs especially for the dry season from Nov. to Mar. It was found out that the parameters, particularly for the advection related parameter, must be recalibrated to accurately produce monthly and annual regional evapotranspiration for this study area.

• Proceedings of the Korea Water Resources Association Conference
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• 2015.05a
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• pp.142-142
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• 2015

저영향개발 기법은 유역개발에 따른 수문 및 환경적 영향을 최소화하기 위해 자연상태를 가급적 보존하고 불투수 면적을 최대한 줄이며, 우수발생 지점에서부터 소규모로 우수를 관리하는 분산식 우수배제 방식을 지향한다. 본 연구의 목적은 이러한 저영향개발 기법을 이용한 도시유역의 우수관리에 관한 효과를 기술적, 경제적 관점에서 정량적으로 평가하는 것이다. 이를 위해 기존 개발 방식으로 계획된 송산 그린시티 동측지구에 저영향개발 기법을 적용하였고, 결과를 기존 개발 방식과 비교하여 저영향개발 기법의 효과를 분석하였다. 대상유역에 대하여 저영향개발 기법을 적용하기 위해 분산식 우수배제 방식을 도입하였고(그림 1), 식생수로와 인공습지 등의 저영향개발 요소기술을 적용하였다(그림 2). 연구에서는 SWMM을 이용하여 저영향개발 기법과 기존 개발 방식에 의한 우수관리를 각각 모의하였고, 모의 결과를 홍수, 물순환, 비점오염 저감의 관점에서 비교 검토하였다(그림 3과 4). 또한, 개략 공사비 산정을 통해 기존 개발 방식 대비 저영향개발 기술의 경제적 효과를 분석하였다. 그 결과, 저영향개발 기법을 적용할 경우, 상대적으로 저 비용으로도 기존 개발 방식에 의한 우수관리보다 더 높은 효과를 달성할 수 있는 것으로 분석되었다.