• 국제초고층학회논문집
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• 제7권4호
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• pp.299-311
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• 2018

As engineered timber such as Glulam is seeing increasing use in tall timber buildings, building codes are adapting to allow for this. In order for this material to be used confidently and safely in one of these applications, there is a need to understand the effects that fire can have on an engineered timber structural member. The post-fire resilience aspect of glulam is studied herein. Two sets of experiments are performed to consider the validity of zero strength guidance with respect to short duration fire exposure on thin glulam members. Small scale samples were heated in a cone calorimeter to different fire severities. These samples illustrated significant strength loss but high variability despite controlled quantification of char layers. Large scale samples were heated locally using a controlled fuel fire in shear and moment locations along the length of the beam respectively. Additionally, reduced cross section samples were created by mechanically carving a way an area of cross section equal to the area lost to char on the heated beams. All of the samples were then loaded to failure in four-point (laterally restrained) bending tests. The beams that have been burnt in the shear region were observed as having a reduction in strength of up to 34.5% from the control beams. These test samples displayed relatively little variability, apart from beams that displayed material defects. The suite of testing indicated that zero strength guidance may be under conservative and may require increasing from 7 mm up to as much as 23 mm.

• The Journal of Asian Finance, Economics and Business
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• 제7권8호
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• pp.213-224
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• 2020

The study assesses the impact of trade liberalization factors on changes in customs revenues in Vietnam. Research data was conducted between 2002 and 2017 on the official website of the Government's Web Portal and The World Bank. This paper uses the vector error correction model to estimate the short-term and long term relationship between data series. The results have proven that tariff reductions have a positive effect on short-term and long-term customs revenues in Vietnam. However, the implementation of other international commitments on trade liberalization has positive short-term and long-term negative impacts on customs revenues in Vietnam. The study's results also show that exchange rate has no effect on changes in customs revenues in the short term but it has a strong impact on increasing customs revenues in the long run. Based on these findings, the article also suggests a number of policies to ensure customs revenues in Vietnam in future. In order to ensure customs revenues, the government of Vietnam should: (1) having some policy to improve the efficiency of customs management in Vietnam; (2) Building appropriate VND exchange rate policy; (3) Establishing reasonable non - tariff barriers to prevent fraud and ovations cause losses in customs revenues.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제13권4호
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• pp.1975-1988
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• 2019

Short-term traffic flow prediction plays an important role in intelligent transportation systems (ITS) in areas such as transportation management, traffic control and guidance. For short-term traffic flow regression predictions, the main challenge stems from the non-stationary property of traffic flow data. In this paper, we design an ensemble cascading prediction framework based on extremely randomized trees (extra-trees) using a boosting technique called EET to predict the short-term traffic flow under non-stationary environments. Extra-trees is a tree-based ensemble method. It essentially consists of strongly randomizing both the attribute and cut-point choices while splitting a tree node. This mechanism reduces the variance of the model and is, therefore, more suitable for traffic flow regression prediction in non-stationary environments. Moreover, the extra-trees algorithm uses boosting ensemble technique averaging to improve the predictive accuracy and control overfitting. To the best of our knowledge, this is the first time that extra-trees have been used as fundamental building blocks in boosting committee machines. The proposed approach involves predicting 5 min in advance using real-time traffic flow data in the context of inherently considering temporal and spatial correlations. Experiments demonstrate that the proposed method achieves higher accuracy and lower variance and computational complexity when compared to the existing methods.

• KIEAE Journal
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• 제14권1호
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• pp.101-111
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• 2014

The Product Carbon Footprint Labeling has been run for more than four years by the Ministry of Environment and there are number of products labeled by KEITI(Korea Environmental Industry & Technology Institute), as for declaring products with their carbon emission during life cycle stages. There are several categories for certifying products by the characteristics of usage. Building products which are applied to a building as combined components or elements, are classified as production goods which means that the products are chosen by a business, not by a final consumer. In this paper, current status of PCF labeling has been reviewed focused on building products and the characteristics of carbon emission by a kind of product such as interior products, window products, structural products, system products and others. Until Dec. 2013, 82 products has been labeled and it covers about 53% among labeled product goods by the certification. Among the labeled building products, interior products are main products. From the results of comparison, variations of emission amounts by products have been found and the cause of variation could be explained by the purpose and material properties of products. However, the exact reason for variations cannot be acquired because of lack of information and the short operation period of the certification program. Further studies and more products are needed to be studied and analyzed focused on the emission characteristic by each product and to suggest reduction technologies for sustainable building products.

• Computers and Concrete
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• 제33권5호
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• pp.595-603
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• 2024

In the construction industry, there has been a surge in the implementation of high-tech equipment in recent years. Various technologies are being considered as potential solutions for future construction projects. Building information modeling (BIM), which utilizes advanced equipment, is a promising solution among these technologies. The need for safety inspection has also increased with the aging structures. Nevertheless, traditional safety inspection technology falls short of meeting this demand as it heavily relies on the subjective opinions of workers. This inadequacy highlights the need for advancements in existing maintenance technology. Research on building safety inspection using 3D laser scanners has notably increased. Laser scanners that use light detection and ranging (LiDAR) can quickly and accurately acquire producing information, which can be realized through reverse engineering by modeling point cloud data. This study introduces an innovative evaluation system for building safety using a 3D laser scanner. The system was used to assess the safety of an existing three-story building by implementing a reverse engineering technique. The 3D digital data are obtained from the scanner to detect defects and deflections in and outside the building and to create an as-built BIM. Subsequently, the as-built structural model of the building was generated using the reverse engineering approach and used for structural analysis. The acquired information, including deformations and dimensions, is compared with the expected values to evaluate the effectiveness of the proposed technique.

• 한국태양에너지학회 논문집
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• 제36권3호
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• pp.75-85
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• 2016

This research aims to predict and analyze green building certification market of Korean Peninsula after unification. First, it analyzes prospected unification time period, then it forecasts number of new residential and non-residential buildings to be constructed based on estimated number of residences in short at the time in North Korea. There exists a good chance that North Korea's new building market forms similar to that of South Korea, as unification would thoroughly proceed which would result levels of economic culture social politics in quasi-equal state. Thus, assuming the ratio of residential and non-residential building against population is similar in both Korea's, the number against North Korea's house supplied population can be estimated. Based on the expected numbers in North Korea, number of proceeded Building Energy Conservation Plan, Building Energy Rating Certification, and Green Standard for Energy and Environmental Design (G-SEED) are predicted. The research shows certification market related to green building in united Korean Peninsula to be \660 billion over 10 years. Not only certifications to newly built buildings but also including existing buildings, this market is to grow to a considerable extent. As this would largely influence eco-constructive materials, energy plant/equipment, and other relevant markets as well, it would require to make thorough preparations. In sum, to stabilize green building market even before the unification, the research proposes the necessities of appropriate systems in consideration of North Korea, through in-depth discussions and establishment of technology and policy directions in green building sector, such as building energy management and emission reduction technology.

• 산업경영시스템학회지
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• 제46권1호
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• pp.84-90
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• 2023

ASL estimation of public building is based on how appropriate the maximum age of the asset is derived based on the age record of the asset in the statistical data owned by public institutions. This is because we get a 'constrained' ASL by that number. And it is especially true because other studies have assumed that the building is an Iowa curve R3. Also, in this study, the survival rate is 1% as the threshold value at which the survival curve and the predictable life curve almost coincide. Rather than a theoretical basis, in the national statistical survey, the value of residual assets was recognized from the net value of 10% of the acquisition value when the average service life has elapsed, and 1% when doubling the average service life has elapsed. It is based on the setting mentioned above. The biggest constraint in fitting statistical data to the Iowa curve is that the maximum ASL is selected at R3 150%, and the 'constrained' ASL is calculated by the proportional expression on the assumption that the Iowa curve is followed. In like manner constraints were considered. First, the R3 disposal curve for the RCC(reinforced cement concrete) building was prepared according to the discarding method in the 2000 work, and it was jointly worked on with the National Statistical Office to secure the maximum amount of vintage data, but the lacking of sample size must be acknowledged. Even after that, the National Statistical Office and the Bank of Korea have been working on estimating the Iowa curve for each asset class in the I-O table. Another limitation is that the asset classification uses the broad classification of buildings as a subcategory. Second, if there were such assets with a lifespan of 115 years that were acquired in 1905 and disposed of in 2020, these discarded data would be omitted from this ASL calculation. Third, it is difficult to estimate the correct Iowa curve based on the stub-curve even if there is disposal data because Korea has a relatively shorter construction history, accumulated economic wealth since the 1980's. In other words, "constrained" ASL is an under-estimation of its ASL. Considering the fact that Korea was an economically developing country in the past and during rapid economic development, environmental factors such as asset accumulation and economic ability should be considered. Korea has a short period of accumulation of economic wealth, and the history of 'proper' architectures faithful to building regulations and principles is short and as a result, buildings 'not built properly' and 'proper' architectures are mixed. In this study, ASL of RCC public building was estimated at 70 years.

• 대한토목학회논문집
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• 제35권6호
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• pp.1229-1236
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• 2015

본 연구에서는 다양한 사행도를 갖는 내성천 하도 구간에 대해 단기 홍수사상 발생시 나타나는 흐름과 하상변동 특성을 2차원 모형인 CCHE2D를 이용하여 분석하였다. 내성천 하도 구간은 사행도가 1.2, 1.6, 2.2인 3개 구간으로 나누어 흐름 및 하상변동 모의를 수행하였으며, 2011년 6월에 발생한 6일 동안의 홍수사상에 대해 모의를 수행하였다. 모의 결과, 사행도가 큰 구간에 비해 사행도가 1.5 미만인 구간에서 흐름 집중현상에 의한 평면적 유속차가 크게 나타났으며, 만곡부에서의 하상침식이 시간에 따라 더 크게 확대된 것을 알 수 있었다. 사행도가 1.5 미만인 구간에서는 최대홍수량이 발생했을 때 최대유속이 국부적으로 1.6 m/s에서 2 m/s 이상인 것으로 나타났다.

• KIEAE Journal
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• 제14권2호
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• pp.69-75
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• 2014

Building has been deteriorated over the year after construction. The deterioration has caused to hinder the living condition and to decrease the building value. Thus, it is important to prevent or delay the building deterioration as well as to proceed the maintenance. The long-term repair program for the apartment in Korea plays a key role to make the repair plan after construction and to assure the function decent. This is not flexible to the change of the material and component because the program is provided by the Korean-law. Many items are omitted in the long-term program so that the maintenance experts face many difficulties to make a repair plan. In this paper, it aimed at providing the repair cycle and repair ratio according to the repair scope, which are not provided in the current program. This study shows that the repair ratio is presented with quartile range in 25%, 50%, 75% and 100%. This has an advantage to take an overall look in repair items. Under this presentation of the repair ratio, each item has a unique repair value. Second, the repair scope is divided into partly repair, fully repair, partly alteration and fully alteration. If a fully repair has a repair ratio close to 100%, it would mean that a fully repair is a fully alteration. Third, the short repair cycle means that it requires to maintain the function or performance of the components in a short term.

• 한국산학기술학회논문지
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• 제16권4호
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• pp.2917-2923
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• 2015

본 논문은 내진성능평가를 위해 사용되는 비탄성해석의 신뢰도와 정확도에 있어 결정적인 영향을 미치는 다양한 이력모델의 특성과 구조물의 내진거동에 미치는 영향을 분석하고자 한다. 연구대상은 표준학교건물로서 우리나라 규준에 맞는 인공지진 가속도 3가지를 사용하여 4가지의 이력모델을 적용하여 3차원 시간이력해석을 수행하였다. 비탄성해석을 통해 층전단력, 층간변위비, 층변위를 비교하고 힌지의 발생 상태를 파악하고 이력모델이 건물의 비탄성거동에 미치는 영향을 분석하였다. 연구 결과, 층전단력은 이력모델에 따라 최대 27%의 차이를 보이고, 층간변위비는 최대 30%의 차이가 나타났다. 장단변방향 모두에서 층전단력과 층간변위비는 최대값이 수정다케다모델에서 나타나 안전율 향상을 기대할 수 있을 것으로 판단된다. 층전단력의 최소값은 장단변방향 모두에서 클러프모델에서, 층간변위비는 장변방향은 다케다모델, 단변방향은 클러프모델에서 나타났고 이 경우 안전율이 낮아질 것으로 사료된다.