• Korean Journal of Construction Engineering and Management
• /
• 제19권5호
• /
• pp.3-9
• /
• 2018

Although Life Cycle Cost (LCC) must be evaluated by experts, sometimes it may not allow a sufficient time for even the experienced LCC expert to make rational decisions. Therefore, it often ends with relatively comparing the final numbers. We have broken down 110 technical proposals that are actually bade and accepted for large construction projects, and then have analyzed the uncertainty of Maintenance and Energy (M&E) cost during building life cycle, which turns out be the most volatile factor in uncertainty of LCC. Also we suggest "Value Engineering Index (VEI)" - the reduced M&E cost that is normalized by the reduced first cost. It is analyzed that the most uncertain factors of the M&E cost include repair and replacement term differing from each project, duplicated repair and replacement, non-standard repair items, and site-specific energy cost. Eventually we propose a VEI population with a mean of 1.38 and a standard deviation of 1.19, which is obtained by individually and exclusively applying the uncertain factors of the M&E cost to the 35 standard sample of technical proposals. The LCC evaluators may be able to use the VEI population as the benchmark to select the technical proposal with the most reasonable LCC among many others in two suggested manners; the one is to deterministically calculate the probability of single VEIs, and the other is to stochastically calculate the probability of the VEIs where uncertainty is quantified.

• Journal of Korean Tunnelling and Underground Space Association
• /
• 제23권5호
• /
• pp.315-323
• /
• 2021

Tunnel is the most energy-consuming structure in road due to the characteristic of using artificial lighting during day and night. Therefore, tunnel lights are being replaced by LED lamp that have advantages with respect to low power consumption. The best use of social overhead capital can be expected by considering the life cycle cost, because to tunnel structures are accompanied by a series of medium-to-long-term and continuous processes of replacing auxiliary facilities. In this study, the saving effect by LCC analysis was quantitatively analyzed by replacing tunnel light sources from high-pressure sodium lamps to LED lamps. The effect of reducing the replacement cycle by increasing the life of the lamps and the resulting maintenance cost is very significant, on replacing tunnel lighting light sources with LED lamp.

• Clinical and Experimental Pediatrics
• /
• 제54권10호
• /
• pp.425-428
• /
• 2011

Ornithine transcarbamylase (OTC) deficiency is well known as the most common inherited disorder of the urea cycle, and 1 of the most common causes of hyperammonemia in newborns. We experienced a case of a 3-day-old boy with OTC deficiency who appeared healthy in the first 2 days of life but developed lethargy and seizure soon afterwards. His serum ammonia level was measured as > $1,700{\mu}g/dL$ (range, 0 to $45{\mu}g/dL$). Continuous renal replacement therapy (CRRT) in the mode of continuous venovenous hemodiafiltration was immediately applied to correct the raised ammonia level. No seizure occurred after the elevated ammonia level was reduced. Therefore, CRRT should be included as 1 of the treatment modalities for newborns with inborn errors of metabolism, especially hyperammonemia. Here, we report 1 case of successful treatment of hyperammonemia by CRRT in a neonate with OTC deficiency.

• Journal of Biomedical Engineering Research
• /
• 제28권1호
• /
• pp.108-116
• /
• 2007

Recently, it has been reported that the posterior stabilized implant, which is clinically used for the total knee replacement (TKR), may have failure risk such as wear or fracture by the contact pressure and stress on the tibial post. The purpose of this study is to investigate the influence of the mal alignment of the posterior stabilized implant on the tibial post by estimating the distributions of contact pressure and von-Mises stress on a tibial post and to analyze the failure risk of the tibial post. Finite element models of a knee joint and an implant were developed from 1mm slices of CT images and 3D CAD software, respectively. The contact pressure and the von-Mises stress applying on the implant were analyzed by the finite element analysis in the neutral alignment as well as the 8 malalignment cases (3 and 5 degrees of valgus and varus angulations, and 2 and 4 degrees of anterior and posterior tilts). Loading condition at the 40% of one whole gait cycle such as 2000N of compressive load, 25N of anterior-posterior load, and 6.5Nm of torque was applied to the TKR models. Both the maximum contact pressure and the maximum von-Mises stress were concentrated on the anterior-medial region of the tibial post regardless of the malalignment, and their magnitudes increased as the degree of the malalignment increased. From present result, it is shown that the malalignment of the implant can influence on the failure risk of the tibial post.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 한국건축시공학회 2016년도 춘계 학술논문 발표대회
• /
• pp.87-88
• /
• 2016

In order to assess the design value of engineering work from the point of view of LCC (Life Cycle Cost) in Korea, it is mandatory for all construction works that the total construction costs are over 10 billion won. The LCC includes initial construction costs, maintenance & operation costs, energy costs, end-of-life costs, and so on. Among these, the portion for maintenance & operation costs for a building is sizeable, as compared to the initial construction costs. Furthermore, the paradigm for construction industry has rapidly shifted from 2D to BIM, which includes design planning and data management. However, the study of BIM-based LCC analysis is not adequate today, even though all domestic construction projects ordered by the Public Procurement Service have to adopt BIM. Therefore, this study suggests a methodology of BIM-based LCC analysis that is particularly focused on repair and replacement (R&R) cost. For this purpose, we defined requirements of calculating R&R cost and extracted X from the relevant IFC data. Thereafter, we input them to the ontology of calculating the initial construction costs to obtain an objective output. Finally, in order to automatically calculate R&R cost, mapping with R&R criteria was performed. We expect that our methodology will contribute to more efficiently calculate R&R cost and, furthermore, that this methodology will be applicable to all range of total LCC. Thus, the proposed process of automatic BIM-based LCC analysis will contribute to making LCC analysis more fast and accurate than it is at present.

• Journal of the Korea Society of Computer and Information
• /
• 제25권2호
• /
• pp.1-10
• /
• 2020

In this paper, we propose an efficient disk buffer replacement policy which improves hit ratio and reduces writing operations of flash based storages. The flash based storage has many advantages, including a small form factor, non-volatility and high reliability, but there are problems caused by own limitations, like not-in-place update, short life cycle and asymmetric I/O latencies. To redeem these problems, this paper proposes the write weighted probability of reference(2WPR) policy. 2WPR policy predicts re-referencing probability and calculates localities of each page. Furthermore, by weighting write operations to every pages, 2WPR can reduce write operations to flash based storage. In addition, we can improve the performance with higher hit ratio and reduce the number of write operations and consequently shorten the latencies of each operation. The results show that our policy provides improvements of up to 10% for the hit ratio with the reduction of up to 5% for the flash writing operation compared with other policies.

• Journal of Korea Multimedia Society
• /
• 제22권5호
• /
• pp.535-546
• /
• 2019

Recently, there have been a lot of researches on the whole face replacement system, but it is not easy to obtain stable results due to various attitudes, angles and facial diversity. To produce a natural synthesis result when replacing the face shown in the video image, technologies such as face area detection, feature extraction, face alignment, face area segmentation, 3D attitude adjustment and facial transposition should all operate at a precise level. And each technology must be able to be interdependently combined. The results of our analysis show that the difficulty of implementing the technology and contribution to the system in facial replacement technology has increased in facial feature point extraction and facial alignment technology. On the other hand, the difficulty of the facial transposition technique and the three-dimensional posture adjustment technique were low, but showed the need for development. In this paper, we propose four facial replacement models such as 2-D Faceswap, OpenPose, Deekfake, and Cycle GAN, which are suitable for the Cox platform. These models have the following features; i.e. these models include a suitable model for front face pose image conversion, face pose image with active body movement, and face movement with right and left side by 15 degrees, Generative Adversarial Network.

• Earthquakes and Structures
• /
• 제26권1호
• /
• pp.77-86
• /
• 2024

To investigate the seismic performance of steel pipe-aeolian sand recycled concrete columns, this study designed and produced five specimens. Low-cycle repeated load tests were conducted while maintaining a constant axial compression ratio. The experiment aimed to examine the impact of different aeolian sand replacement rates on the seismic performance of these columns. The test results revealed that the mechanical failure modes of the steel pipe-recycled concrete column and the steel pipe-aeolian sand recycled concrete column were similar. Plastic hinges formed and developed at the column foot, and severe local buckling occurred at the bottom of the steel pipe. Interestingly, the bulging height of the damaged steel pipe was reduced for the specimen mixed with an appropriate amount of wind-deposited sand under the same lateral displacement. The hysteresis curves of all five specimens tested were relatively full, with no significant pinching phenomenon observed. Moreover, compared to steel tube-recycled concrete columns, the steel tube-aeolian sand recycled concrete columns exhibited improved seismic energy dissipation capacity and ductility. However, it was noted that as the aeolian sand replacement rate increased, the bearing capacity of the specimen increased first and then decreased. The seismic performance of the specimen was relatively optimal when the aeolian sand replacement rate was 30%. Upon analysis and comparison, the damage analysis model based on stiffness and energy consumption showed good agreement with the test results and proved suitable for evaluating the damage degree of steel pipe-wind-sand recycled concrete structures.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• 제14권8호
• /
• pp.4033-4038
• /
• 2013

Sedimentary rocks from construction waste are discarded through open storage and landfilling, which causes an increase in construction cost and inefficient of execution of works. Some sandstone are selected and utilized as aggregates, but shale is buried as industrial waste. Therefore, in this research, we evaluated weathering properties of shale aggregate that is widely distributed throughout Daegu-Kyeongbuk region and freeze-thaw characteristics of concrete according to the replacement ratio of shale aggregate, in an effort to stabilize aggregate supply-demand in Daegu-Kyeongbuk region and develop alternative aggregates. We used red shale and black shale in the experiment, which were exported from a construction site in Deagu. We verified the usage of shale as a concrete aggregate by comparing andesite, which is broadly used as a thick aggregate for concrete, to hornfels, which is a metamorphic sedimentary rock. As a result of the experiment, we observed no degradation phenomenon for andesite and hornfels. However, a part of country rock containing black shale was found to be exfoliated. Red shale started having cracks in the direction of stratification after 1.5 months of direct exposure, and it broke into smaller pieces after approximately 4 months. After 300 cycles of freeze-thaw process on the concrete manufactured according to the replacement ratio of shale aggregate, the modulus of elasticity was 97% for plain and 95% for hornfels. In the case of RS_100, it was 57% after 210 cycles, and for BS_100, it was 54% after 240 cycles. Therefore, we established that, as the number of repetition increases, the freeze-thaw resistance decreases dramatically.

• 한국사회정책
• /
• 제23권1호
• /
• pp.203-225
• /
• 2016

The permanent disability benefit(PDB) system whose purpose lies in helping affected workers with their self-realization through compensating them for their work-related injury or disease and facilitating their timely return to work is very important in terms of social welfare. Actually, the portions of PDB's in all WCI expenditures have been on the sharp increase. In spite of its positive aspects like this, however, an excessive amount of PDB's may have negative impacts on the affected workers' will to work or return to work, and increasing trends in the amount of PDB's payable in annuity will remain in an aging or aged society a potentially risky factor posing a threat to the soundness of WCI budgets. In this respect, the author attempted herein to identify the long-term reality of trends in the number of claimants entitled to PDB's and the amount of PDB's payable to them through making the long-term budget projections of PDB's; address problems with PDB's payable in annuity, which are or will potentially be one of the gravest burdens in securing the soundness of WCI budgets; and discuss how to optimize the amount of PDB's through studying & analyzing overseas cases and income replacement rates and what kinds of improvements are thinkable. It's recommended to reduce the absolute amount of benefits payable in annuity in a phased way considering claimants' life-cycle instead of sticking to the current system, which takes the form of lifelong pension plan.