• Computers and Concrete
• /
• v.23 no.6
• /
• pp.433-444
• /
• 2019

As rice husk ash (RHA) is not produced in controlled manufacturing process like cement, its properties vary significantly even within the same lot. In fact, properties of Rice Husk Ash Based Concrete (RHABC) are largely dictated by uncertainty leading to huge deviations from their expected values. This paper proposes a Robust Cost Optimization (RCO) procedure for RHABC, which minimizes such unwanted deviation due to uncertainty and provides guarantee of achieving desired strength and workability with least possible cost. The RCO simultaneously minimizes cost of RHABC production and its deviation considering feasibility of attaining desired strength and workability in presence of uncertainty. RHA related properties have been modeled as uncertain-but-bounded type as associated probability density function is not available. Metamodeling technique is adopted in this work for generating explicit expressions of constraint functions required for formulation of RCO. In doing so, the Moving Least Squares Method is explored in place of conventional Least Square Method (LSM) to ensure accuracy of the RCO. The efficiency by the proposed MLSM based RCO is validated by experimental studies. The error by the LSM and accuracy by the MLSM predictions are clearly envisaged from the test results. The experimental results show good agreement with the proposed MLSM based RCO predicted mix properties. The present RCO procedure yields RHABC mixes which is almost insensitive to uncertainty (i.e., robust solution) with nominal deviation from experimental mean values. At the same time, desired reliability of satisfying the constraints is achieved with marginal increment in cost.

• Nuclear Engineering and Technology
• /
• v.56 no.1
• /
• pp.123-131
• /
• 2024

Electron paramagnetic resonance (EPR) dosimetry for a tooth from an individual exposed is well known as retrospective dosimetry in radiological accidents. A major constraint of the conventional X-band tooth-EPR dosimetry is the necessity to extract the tooth of the exposed patient for dose assessment. In this study, to conduct the dose assessments of exposed patients through part-extraction of tooth enamel, the minimum detectable dose (MDD) of the tooth enamel was evaluated based on the amount of mass. Further, a field test was conducted via intercomparison using various dose assessment methods to verify the feasibility of X-band tooth-EPR dosimetry using the minimum mass of tooth enamel. The intercomparison results demonstrated that effective dose determination via X-band tooth-EPR dosimetry is reliable. Consequently, it was determined that the minimum mass of tooth enamel required to evaluate an absorbed dose above 0.5 Gy is 15 mg. Thus, EPR dosimetry using 15 mg of tooth enamel can be applied in the triage and initial medical response stages for patients exposed during radiological accidents. This approach represents an advancement in managing radiological accidents by offering a more efficient and less invasive method of dose assessment.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.42 no.5
• /
• pp.430-436
• /
• 2014

The mission objective of STEP Cube Lab. (Cube Laboratory for Space Technology Experimental Project) classified as a pico-class satellite is to verify the technical effectiveness of payloads such as variable emittance radiator, SMA washer, oscillating heat pipe and MEMS based solid propellant thruster researched at domestic universities. In addition, the MEMS concentrating photovoltaic power system and the non-explosive holding and separation mechanism with the advantages of high constraint force and low shock level will be developed as the primary payloads for on-orbit verification. In this study, the feasibility of the mission actualization has been confirmed by the preliminary system design.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.40 no.5
• /
• pp.527-534
• /
• 2020

A significant factor in construction work is cost. At early- and advanced-stage design, costs should be calculated to derive realistic cost estimates according to unit price calculation. Based on these estimates, the economic feasibility of construction work is assessed, and whether to proceed is determined. Through the Korea Institute of Civil Engineering and Building Technology, the construction cost index has been calculated by indirect methods after both the producer price index and construction market labor have been reprocessed to easily adjust the price changes of construction costs in Korea, and the Institute has announced it since 2004. As of January 2000, however, the construction cost index was released, and this has a time constraint on the correction and use of past construction cost data to the present moment. Variables were calculated to compute a rough construction cost that utilized past construction costs through surveys of the producer price index and the construction market labor force consisting of the construction cost index. After significant independent variables among the many variables were selected through correlation analysis, the construction cost index from 1970 to 1999 was calculated and presented through multiple regression analysis. This study therefore has prominent significance in terms of proposing a method of calculating rough construction costs that utilize construction costs that pre-date the 2000s.

• Journal of Broadcast Engineering
• /
• v.10 no.4 s.29
• /
• pp.528-539
• /
• 2005

The H.264 has been adopted as the video codec for various multimedia services such as DMB and next-generation DVD because of its superior coding performance. However, the reference codec of the standard, the joint model (JM) contains quite a few algorithms which are too complex to be used for the resource-constraint embedded environment. This paper introduces very low-complexity H.264 encoding algorithm which is applicable for the embedded environment. The proposed algorithm was realized by restricting some coding tools on the basis that it should not cause too severe degradation of RD-performance and adding a few early termination and bypass conditions during the motion estimation and mode decision process. In case of encoding of 7.5fps QCIF sequence with 64kbpswith the proposed algorithm, the encoder yields worse PSNRs by 0.4 dB than the standard JM, but requires only $15\%$ of computational complexity and lowers the required memory and power consumption drastically. By porting the proposed H.264 codec into the PDA with Intel PXA255 Processor, we verified the feasibility of the H.264 based MMS(Multimedia Messaging Service) on PDA.

• Strategy21
• /
• s.43
• /
• pp.29-55
• /
• 2018

Arctic sea ice has been retreating as a result of the global warming. Arctic sea ice extent for April 2018 averaged 13.71 million square kilometers. This figure shows far less sea ice compared to the average extent from 1981 to 2010. Meanwhile, 287 times of maritime transits through the Northwest Passage have been made during the 2017 and the first ship traversed the Northern Sea Route without the assistant of ice-breaker in August 2017. Commercialization of the Arctic Passage means significant economic and strategic advantages by shortening the distance. In this article, 'Arctic Passage' means Northern Sea Route along the Arctic coast of Russia and Northwest Passage crossing Canadian Arctic Ocean. As climate changes, the potential feasibility of the Arctic Passage has been drawing international attention. Since navigation in this area remains hazardous in some aspects, IMO adopted Polar Code to promote safe, secure and sustainable shipping through the Arctic Passage. Futhermore, Russia and Canada regulate foreign vessels over the maritime zones with the authority to unilaterally exercise jurisdiction pursuant to the Article 234 of UNCLOS. The dispute over the navigation regime of the arctic passage materialized with Russia proclaimed Dmitrii Laptev and Sannikov Straits as historically belong to U.S.S.R. in the mid 1960s and Canada declared that the waters of the passage are historic internal waters in 1973 for the first time. So as to support their claims, In 1985, Russia and Canada established straight baseline including Northern Sea Route and Northwest Passage. The United States has consistently protested that the Northern Sea Route and Northwest Passage are straits used for international navigation which are subject to the regime of transit passage. Firstly, it seems that Russia and Canada do not meet the basic requirements for acquiring a historic title. Secondly, since the Law of the Sea had adopted before the establishment of straight baseline over the Russian Arctic Archipelago and the Canadian Arctic Archipelago, Ships can exercise at least the right of innocent passage. Lastly, Northern Sea Route and Northwest Passage have fulfilled the both geographical and functional criteria pertaining to the strait used for international navigation under the international law. Especially, should the arctic passage become commercially viable, it can be expected to accumulate the functional criterion. Russia and Canada regulate the ships navigate in their maritime zones by adopting the higher degree of an environmental standard than generally accepted international rules and standard mainly under the Article 234 of UNCLOS. However, the Article 234 must be interpreted restrictively as this contains constraint on the freedom of navigation. Thus, it is reasonable to consider that the Article 234 is limited only to the EEZ of coastal states. Therefore, ships navigating in the Arctic Passage with the legal status of the territorial sea and the international straits under the law of the sea have the right of innocent passage and transit passage as usual.

• Asian Pacific Journal of Cancer Prevention
• /
• v.16 no.8
• /
• pp.3257-3265
• /
• 2015

Background: Radiotherapy is an important treatment of choice for breast cancer patients after breast-conserving surgery, and we compare the feasibility of using dual arc volumetric modulated arc therapy (VMAT2), single arc volumetric modulated arc therapy (VMAT1) and Multi-beam Intensity Modulated Radiotherapy (M-IMRT) on patients after breast-conserving surgery. Materials and Methods: Thirty patients with breast cancer (half right-sided and half left-sided) treated by conservative lumpectomy and requiring whole breast radiotherapy with tumor bed boost were planned with three different radiotherapy techniques: 1) VMAT1; 2) VMAT2; 3) M-IMRT. The distributions for the planning target volume (PTV) and organs at risk (OARs) were compared. Dosimetries for all the techniques were compared. Results: All three techniques satisfied the dose constraint well. VMAT2 showed no obvious difference in the homogeneity index (HI) and conformity index (CI) of the PTV with respect to M-IMRT and VMAT1. VMAT2 clearly improved the treatment efficiency and can also decrease the mean dose and V5Gy of the contralateral lung. The mean dose and maximum dose of the spinal cord and contralateral breast were lower for VMAT2 than the other two techniques. The very low dose distribution (V1Gy) of the contralateral breast also showed great reduction in VMAT2 compared with the other two techniques. For the ipsilateral lung of right-sided breast cancer, the mean dose was decreased significantly in VMAT2 compared with VMAT1 and M-IMRT. The V20Gy and V30Gy of the ipsilateral lung of the left-sided breast cancer for VMAT2 showed obvious reduction compared with the other two techniques. The heart statistics of VMAT2 also decreased considerably compared to VMAT1 and M-IMRT. Conclusions: Compared to the other two techniques, the dual arc volumetric modulated arc therapy technique reduced radiation dose exposure to the organs at risk and maintained a reasonable target dose distribution.

• The Journal of the Korea institute of electronic communication sciences
• /
• v.17 no.6
• /
• pp.1145-1156
• /
• 2022

In order to effectively secure site suitability for the development of large-scale offshore wind farms, it is essential to minimize the environmental impact of development and analyze the conflicts of benefit between social, ecological, and economic core values. In addition, a preliminary review of site adequacy must be preceded in order not to collide with other used areas in the marine spatial plan. In addition, it is necessary to conduct local meteorological characteristics analysis including wind resources near Jeollanam-do area before project feasibility study. Therefore, wind resource analysis was performed using the observation data of the meteorological mast installed in Wangdeungnyeo near Anmado, Yeonggwang, and the optimal site was selected after excluding geographical constraints related to the location of the offshore wind farm. In addition, the annual energy production was calculated by deriving the optimal wind farm arrangement results suitable for the local wind resources characteristics based on WindSim SW, and it is intended to be used as basic research data for site discovery and selection of suitable sites for future offshore wind farm projects.

• Progress in Medical Physics
• /
• v.26 no.2
• /
• pp.79-86
• /
• 2015

The purpose of this study is to evaluate efficacy and feasibility of adaptive radiotherapy according to tumor volume change (TVC) in early stage non-small cell lung cancer (NSCLC) using stereotactic body radiotherapy (SBRT). Twenty-two lesions previously treated with SBRT were selected. SBRT was usually performed with a total dose of 48 Gy or 60 Gy in four fractions with an interval of three to four days between treatments. For evaluation of TVC, gross tumor volume (GTV) was contoured on each cone-beam computed tomography (CBCT) image used for image guidance. Intensity modulated radiotherapy (IMRT) planning was performed in the first CBCT (CBCT1) using a baseline plan. For ART planning (ART), re-optimization was performed at $2^{nd}$, $3^{rd}$, and $4^{th}$ CBCTs (CBCT2, CBCT3, and CBCT4) using the same angle and constraint used for the baseline plan. The ART plan was compared with the non-ART plan, which generated copying of the baseline plan to other CBCTs. Average GTV volume was 10.7 cc. Average TVC was -1.5%, 7.3%, and -25.1% in CBCT2, CBCT3, and CBCT4 and the TVC after CBCT3 was significant (p<0.05). However, the nine lesions were increased GTV in CBCT2. In the ART plan, $V_{20\;Gy}$, $D_{1500\;cc}$, and $D_{1000\;cc}$ of lung were significantly decreased (p<0.05), and $V_{30\;Gy}$ and $V_{32\;Gy}$ of the chest wall were also decreased (p<0.05). While D min of planning target volume (PTV) decreased by 8.3% in the non-ART plan of CBCT2 compared with the baseline plan in lesions with increased tumor size (p=0.021), PTV coverage was not compromised in the ART plan. Based on this result, use of the ART plan may improve target coverage and OAR saving. Thus ART using CBCT should be considered in early stage NSCLC with SBRT.

• Journal of Broadcast Engineering
• /
• v.8 no.4
• /
• pp.325-338
• /
• 2003

Video adaptation in response to dynamic resource conditions and user preferences is required as a key technology to enable universal multimedia access (UMA) through heterogeneous networks by a multitude of devices In a seamless way. Although many adaptation techniques exist, selections of appropriate adaptations among multiple choices that would satisfy given constraints are often ad hoc. To provide a systematic solution, we present a general conceptual framework to model video entity, adaptation, resource, utility, and relations among them. It allows for formulation of various adaptation problems as resource-constrained utility maximization. We apply the framework to a practical case of dynamic bit rate adaptation of MPEG-4 video streams by employing combination of frame dropping and DCT coefficient dropping. Furthermore, we present a descriptor, which has been accepted as a part of MPEG-21 Digital Item Adaptation (DIA), for supporting terminal and network quality of service (QoS) in an interoperable manner. Experiments are presented to demonstrate the feasibility of the presented framework using the descriptor.