• KSII Transactions on Internet and Information Systems (TIIS)
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• v.12 no.7
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• pp.3095-3111
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• 2018

Spectrum sensing (SS) is one of the fundamental tasks for cognitive radio. In SS, decisions can be made via comparing the test statistics with a threshold. Conventional adaptive algorithms for SS usually adjust their thresholds according to the radio environment. This paper concentrates on the issue of adaptive SS whose threshold is adjusted based on the Markovian behavior of primary user (PU). Moreover, Bayesian cost is adopted as the performance metric to achieve a trade-off between false alarm and missed detection probabilities. Two novel adaptive algorithms, including Markov Bayesian energy detection (MBED) algorithm and IMBED (improved MBED) algorithm, are proposed. Both algorithms model the behavior of PU as a two-state Markov process, with which their thresholds are adaptively adjusted according to the detection results at previous slots. Compared with the existing Bayesian energy detection (BED) algorithm, MBED algorithm can achieve lower Bayesian cost, especially in high signal-to-noise ratio (SNR) regime. Furthermore, it has the advantage of low computational complexity. IMBED algorithm is proposed to alleviate the side effects of detection errors at previous slots. It can reduce Bayesian cost more significantly and in a wider SNR region. Simulation results are provided to illustrate the effectiveness and efficiencies of both algorithms.

• Structural Engineering and Mechanics
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• v.75 no.2
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• pp.271-282
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• 2020

The preservation of historic masonry-arch railway bridges is of paramount importance due to their economic benefits. These bridges which belong to past centuries may nowadays be expected to carry loads higher than those for which they were designed. Such an increase in loads may be because of increase in transportation speed or in the capacity of freight-wagons. Anyway, adequate increase in their load-carrying-capacity through structural-strengthening is required. Moreover, the increasing costs of material/construction urge engineers to optimize their designs to obtain the minimum-cost one. This paper proposes a novel numerical optimization method to minimize the costs associated with strengthening of masonry-arch railway bridges. To do so, the stress/displacement responses of Sahand-Goltappeh bridge are assessed under ordinary train pass as a case study. For this aim, 3D-Finite-Element-Model is created and calibrated using experimental test results. Then, it is strengthened such that following goals are achieved simultaneously: (1) the load-carrying-capacity of the bridge is increased; (2) the structural response of the bridge is reduced to a certain limit; and, (3) the costs needed for such strengthening are minimized as far as possible. The results of the case study demonstrate the applicability/superiority of the proposed approach. Some economic measures are also recommended to further reduce the total strengthening cost.

• Journal of Distribution Science
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• v.18 no.10
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• pp.53-64
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• 2020

Purpose: With the emergence of high technology in China, online shopping distribution of fresh agricultural products have been developing rapidly. This study built a model to investigate how perceived quality of products and logistic services, perceived risk, and perceived cost affect intention to buy fresh agricultural products in an Internet environment. Especially, in the purchasing process, attitude may work as an important mediator. Research design, data and methodology: To achieve the objectives of this study, Chinese respondents were asked to fill in a questionnaire through the China online survey website. With 520 available data, regression analysis was used to test the hypotheses. Results: Results indicate that perceived quality of fresh agriculture products and perceived logistics service quality have a significant positive impact on attitude and purchase intention. Results also reveal that perceived risk and perceived cost affect attitude and purchase intention negatively. Finally, results imply that attitude has a positive effect on purchase intention, which is the unique mediator in the online shopping process. Conclusions: This study suggests that managers in the online shopping distributions of fresh agricultural products should improve the quality of products and logistics services along with the reduction of the perceived risk and cost to compete in the China market.

• Transactions of the Korean Society of Automotive Engineers
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• v.13 no.2
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• pp.108-113
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• 2005

The damageability and repairability of similar platform type vehicles could be very concerned with design optimization. In all the vehicles crash tested, small size passenger vehicles were weakness in aspect of damageability and repairability. The most critical area appears to be repair cost considering that parts cost is the largest portion of total repair cost segments. Besides repair cost, attaching method of front sidemember and subframe are placed special importance for impact energy absorption and damageability and repairability. So in order to improve damageability and repairability of vehicle structure and body component of the monocoque type passenger vehicles, the end of front side member and front back beam should be designed with optimum level and to supply the end of front side member as a partial condition approx 300mm. The effectiveness of design concept on the 40% offset frontal impact characteristics of the passenger vehicle structure is investigated and summarized.

• Journal of Auto-vehicle Safety Association
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• v.12 no.2
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• pp.33-39
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• 2020

This paper presents an Around View Monitoring (AVM) stop-line detection based longitudinal position correction algorithm for automated driving on urban roads. Poor positioning accuracy of low-cost GPS has many problems for precise path tracking. Therefore, this study aims to improve the longitudinal positioning accuracy of low-cost GPS. The algorithm has three main processes. The first process is a stop-line detection. In this process, the stop-line is detected using Hough Transform from the AVM camera. The second process is a map matching. In the map matching process, to find the corrected vehicle position, the detected line is matched to the stop-line of the HD map using the Iterative Closest Point (ICP) method. Third, longitudinal position of low-cost GPS is updated using a corrected vehicle position with Kalman Filter. The proposed algorithm is implemented in the Robot Operating System (ROS) environment and verified on the actual urban road driving data. Compared to low-cost GPS only, Test results show the longitudinal localization performance was improved.

• The Journal of Information Technology
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• v.9 no.4
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• pp.75-85
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• 2006

This study is to test the influence of stock option granting information on the firm's performance. The important issue in stock option is that agent cost is the important determinant factor for the long term performance. The agent cost arises between the manager and shareholders. So many study are concentrated in diminishing the agent cost, and develop some substitute tools to measure the agent cost. The event study about stock option analyzes returns around event date at a time. Event study provides estimation periods and cumulative returns. Announcements about stock option are generally associated with positive abnormal returns in short term period, but not showing positive effect in long term period. It is important to investigate the responses of stocks to new information contained in the announcements of stock option. Therefore it is important to study the long term performance in the case of stock option. The event time portfolio approach exists the CAR model, BHAR model and WR model. And the calendar time portfolio approach has the 3 factor model, 4 factor model, CTAR model, and RATS model. This study is forced to develop and arrange two approach method in evaluating the performance, the event time portfolio approach and calendar time portfolio approach.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.65 no.2
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• pp.264-268
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• 2016

Recently, various energy efficiency optimization activities are ongoing globally by integrating conventional grids with ICT (Information and Communication Technology). In this sense, various smart grid projects, which power suppliers and consumers exchange useful informations bilaterally in real time, have been being carried out. The electric vehicle diffusion program is one of the projects and it has been spotlighted because it could resolve green gas problem, fuel economy and tightening environmental regulations. In this paper, the economics of V2G system which consists of electric vehicles and the charging infrastructure is evaluated comparing electric vehicles for V2G with common electric vehicles. Additional benefits of V2G are analyzed in the viewpoint of load leveling, frequency regulation and operation reserve. To find this benefit, electricity sales is modeled mathematically considering depth of discharge, maximum capacity reduction, etc. Benefit and cost analysis methods with the modeling are proposed to decide whether the introduction of V2G systems. Additionally, the methods will contribute to derive the future production and the unit cost of electric vehicle and battery and to get the technical and economic analysis.

• Journal of the Society of Naval Architects of Korea
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• v.42 no.5 s.143
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• pp.542-549
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• 2005

Naval ships are complex weapon systems which play the integrated performance by system integration of many kinds of weapon systems and their leading ships are usually not disposed after test and evaluation but militarised. Then, strict project management is required for naval ship building projects by identifying problems early and by taking prefer measures in time against unexpected situations encountered in the process of the projects. EVMS is a project management system which can manage the schedule and the budget of a project concurrently and estimate the project's time duration and the cost at project completion. In this paper, the applicability and usefulness of WMS is studied for a assumed navai ship building project, in the environment of monetary fluctuations such as price index, wage increase rate and exchange rate.

• Korean Journal of Radiology
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• v.20 no.1
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• pp.166-170
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• 2019

Objective: To establish a cost-effective and easily available phantom for training residents in ultrasound-guided fine needle thyroid nodule targeting punctures. Materials and Methods: Tofu, drinking straws filled with coupling gel, a urine tube, and 21-gauge needles were used to generate a phantom thyroid with nodules for training. Twelve radiology residents were involved in the study. The puncture success rates were recorded and compared before and after phantom training using the Wilcoxon signed-rank test. Results: On ultrasonography, tofu mimicked the texture of the thyroid. Drinking straws filled with coupling gel mimicked vessels. The urine tube filled with air mimicked the trachea, and 21-gauge needles mimicked small nodules in the transverse section. The entire phantom was similar to the structure of the thyroid and surrounding tissues. The puncture success rates of radiology residents were significantly increased from 34.4 ± 14.2% to 66.7 ± 19.5% after training (p = 0.003). The phantom was constructed in approximately 10 minutes and materials cost less than CNY 10 (approximately $ 1.5) at a local store. Conclusion: The tofu model was cost-effective, easily attainable, and effective for training residents in ultrasound-guided fine needle thyroid nodule targeting punctures in vitro.

• Journal of Korean Academy of Nursing Administration
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• v.11 no.4
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• pp.449-467
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• 2005

Purpose: This study aims to offer the fundamental data in order to cost the nursing service on the basis of the NIC and a close examination of the interventions that are contained in the health insurance cost list under the system of the current health insurance. Methods: The data is handled with the SPSS 10.0 program. The participants' general peculiarity is calculated in terms of the real number and the percentage, and the performing frequency of the nursing interventions is calculated in terms of the mean and the standard deviation. the correlation between the participants' general peculiarity and the performing frequency of the nursing interventions is analysed with t-test or one way ANOVA of SPSS. Results: In the performing frequency of the nursing interventions, the domain of "the physiological: basic" was the highest as 2.69${\pm}$1.21, the domain of "the behavioral" was the lowest as 2.11${\pm}$1.12. There were 50 core interventions in the medical unit, 48 in the surgical unit, 24 in the MICU and 33 in the SICU. The health insurance cost items contained commonly in the core interventions of each unit were 12, and the health insurance cost items except 12 items contained commonly in the core interventions of each unit were appeared 14 items in the medical unit, 6 in the surgical unit, 7 in the MICU and 2 in the SICU. The core interventions contained commonly in four units of the medical unit, the surgical unit, the MICU & the SICU are 18. And among these, the core interventions contained in the health insurance cost items are 10; pain management, hyperglycemia management, analgegic administration, medication administration: intravenous, oxygen therapy, pressure ulcer prevention, fluid management, fluide monitoring, intravenous(IV) insertion, intravenous(IV) therapy. As the result of the comparison & analysis between the core interventions of the NIC and the health insurance cost items, the core interventions contained in the health insurance cost list are 21(29 as the health insurance cost items). Conclusion: In the performing frequency of the nursing interventions, the domain of "the physiological: basic" is being performed most frequently, and in the performing frequency of the core interventions, the interventions of the domain of "the physiological: complex" is being performed most frequently. On the basis of these results, the writer hopes that the attempts to interlink the nursing interventions into the nursing cost by using of standard terms and the efforts to cost the nursing services would also be made in the future constantly.