• The Journal of the Korea Contents Association
• /
• v.21 no.2
• /
• pp.113-120
• /
• 2021

RFID (Radio Frequency Identification) yoking authentication provides methods scanning a pair of RFID tags with a reader device and verifying them to ensure the physical proximity of objects. In the first yoking proof protocols, a verifier connected to a reader device online is essential to verify the yoking proof, and this condition limits the environment in which yoking proof can be applied. To solve this limitation, several studies have been conducted on offline yoking proof protocol that does not require the online connection between a reader and a verifier. However, the offline yoking proof protocols do not guarantee the basic requirements of yoking proof, and require relatively more operations on the tag compared to the previous yoking proof protocols. This paper proposes an efficient offline yoking proof protocol that supports offline verification without the need for an online verifier. The proposed protocol provides a secure yoking proof with fewer number of operations than the existing ones, and it also can be extended to the group proof for more than a pair of tags without additional devices. The analysis in this paper shows that the proposed protocol provides offline verification securely and effectively.

• Korean Management Science Review
• /
• v.20 no.2
• /
• pp.197-204
• /
• 2003

Comparison challenge approach is proposed as a form of challenger-activated. just-in-time Internet advertising. To develop a framework for a comparison challenge, we propose a theory of comparison value. A comparison is regarded valuable if a comparison opportunity is available and if the comparison is relevant and informative, has an appropriate level of detail, and is advantageous and trustworthy. Based on this theory, the CompareMe and CompareThem strategies are devised, and comparable objects are classified in terms of price and performance dominance as well as the scope of proximity. The idea is demonstrated with a comparison of PCs from five leading manufacturers. To assist in the planning of the comparison challenge, a mathematical programming model was formulated to maximize the value of comparison under the constraints of the comparison opportunity and budget. The model is applied to eight scenarios in terms of the range of comparing objects. The models under various scenarios are tested and contrasted with the real-world example of PCs. We found the ad effect of comparison challenge to be substantially better than banners (4.75 times) and similarity-based comparisons (2.77 times), providing customers with better performance and reduced prices.

• International Journal of Aeronautical and Space Sciences
• /
• v.16 no.1
• /
• pp.77-88
• /
• 2015

The dynamics of relative motion in a perturbed orbital environment are exploited based on Gauss' and Cowell's variational equations. The inertial coordinate frame and relative coordinate frame (Hill frame) are used, and a linear high fidelity model is developed to describe the relative motion. This model takes into account the primary gravitational and atmospheric drag perturbations. Then, this model is used in the design of a navigation, guidance, and control system of a chaser vehicle to approach towards and to depart from a target vehicle in proximity operations. Relative navigation uses an extended Kalman filter based on this relative model to estimate the relative position/velocity of the chaser vehicle with respect to the target vehicle. This filter uses the range and angle measurements of the target relative to the chaser from a simulated LIDAR system. The corresponding measurement models, process noise matrix, and other filter parameters are provided. Numerical simulations are performed to assess the precision of this model with respect to the full nonlinear model. The analyses include the navigation errors and trajectory dispersions.

• Journal of Korea Trade
• /
• v.24 no.2
• /
• pp.68-82
• /
• 2020

Purpose - This study investigates the impact of inland port development in China on the promotion of bilateral trade flows between China and South Korea. Design/methodology - The probable association between the establishment of inland ports and Sino-Korea trade was estimated using gravity models. In this regards, two sets of data were collected. The first dataset consists of the baseline variables of a gravity model, while the second one includes variables of logistics infrastructure development. The indicators of logistics infrastructure development include inland ports, the amount of government expenditure on transport infrastructure, the lengths of roads and railways, the number of trucks and the number of logistics industry workforce. Findings - The results show that inland port development has a positive impact on facilitating bilateral trade between China and South Korea. However, the positive association holds only for Chinese regions with a large trade volume and a proximity to seaports. In other regions, the impact of inland ports is not statistically significant. Originality/value - To the best knowledge of the authors, this study is the first attempt to explore the economic impact of inland ports in China. In addition, the findings in this paper provide both policy and managerial implications for the future development of inland ports, such as the strategic location of inland ports and integrated intermodal operations.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2021.06a
• /
• pp.206-206
• /
• 2021

The necessity for appropriate management of water resources infrastructures such as reservoirs, levees, and dikes is increasing due to unexpected hydro-climate irregularities and rising water demands. To meet this need, past studies have focused on advancing theoretical optimization algorithms such as nonlinear programming, dynamic programming (DP), and genetic programming. Yet, the optimally derived theoretical solutions are limited to be directly implemented in making release decisions in the real-world systems for a variety of reasons. This study first aims to comparatively analyze the two prominent optimization methods, DP and evolutionary multi-objective direct policy search (EMODPS), under historical inflow series using K-fold cross validation. A total of six optimization models are formed each with a specific formulation. Then, one of the optimization models was coupled with the actual zone-based hedging rule that has been adopted in practice. The proposed methodology was applied to Boryeong Dam located in South Korea with conflicting objectives between supply and demand. As a result, the EMODPS models demonstrated a better performance than the DP models in terms of proximity to the ideal. Moreover, the incorporation of the real-world policy with the optimal solutions improved in all indices in terms of the supply side, while widening the range of the trade-off between frequency and magnitude measured in the sides of demand. The results from this study once again highlight the necessity of closing the gap between the theoretical solutions with the real-world implementable policies.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.38 no.2
• /
• pp.269-281
• /
• 2018

Unlike its archetype predecessor such as the Highway Capacity Manual of the United States, the Korean Highway Capacity Manual of 2013 provides the analytical models for estimating the saturation flow rates for the lane-occupying work-zones in the proximity of the signalized intersections. Direct application of the revised saturation flow rates into the classic control delay models, however, appears to produce unreasonable delay amount as traffic demand approaches lane-group capacities and surpasses them, which is common phenomena in the work-zones. Complex interaction among vehicles, lane-dropping work-zone geometry and signal operations were never accounted in the traditional control delay models, and considerable differences between the delay model outcomes and field observations are repeatedly experienced. This paper proposes the modified approaches to the delay models in the manual, exerted on all three elements of control delay, and particularly focuses on the temporal and spatial boundary expansion in comparing the simulated results to the estimated ones. Extensive microscopic simulation work and calibration effort supports the modified approaches well enough to use them in the work-zone planning and evaluation.

• Tunnel and Underground Space
• /
• v.25 no.3
• /
• pp.221-230
• /
• 2015

This study examined and analyzed several mine management software programs developed in domestic and oversea countries. In the oversea countries, many companies have developed and commercialized mine management softwares such as Dispatch, $Cat^{(R)}$ $MineStar^{TM}$ and FARA. These softwares provide many functionalities including real-time machine tracking, machine assignment optimization, productivity management, equipment health monitoring and remote control. For the domestic cases, this study reviewed two software programs (i.e., GEMISIMS, Truck-Shovel fleet optimization) developed by several researchers because there is no mine management software currently commercialized in Korea. In addition, this paper reports the two cases at the Jwaneng mine in Botswana and at the Robinson mine in United States where mine management software programs are used to support mine operations.

• Journal of Radiation Protection and Research
• /
• v.39 no.4
• /
• pp.213-217
• /
• 2014

Medical operations and diagnosis using interventional radiology techniques have been increased. The management and monitoring of occupational radiation exposure to the staff of interventional radiology become important, specially because they stand in close proximity to the patient. The operational radiation protection quantity, Hp(10) which can be obtained from personal dosimeter do not always represent the effective dose to the staff. So, in this study, to estimate the critical organ doses to the staff of interventional radiology, Monte Carlo calculations with mathematical human phantom and dose measurements with personal dosimeters were carried out for the major interventional radiology procedures using C-arm. Results showed that the values of Hp(10) measured by personal dosimeters were higher than critical organ doses which were calculated. And the calculated dose to thyroids was much higher than those of other critical organ doses. For the proper radiation protection of the medical staff of interventional radiology, additional radiation protection for thyroids as well as for whole body shielding like wearing a lead apron should be considered.

• Journal of Aerospace System Engineering
• /
• v.13 no.5
• /
• pp.49-56
• /
• 2019

The Long-Term Sustainability (LTS) guidelines have attracted the most attention in the recent formation of international norms of behavior regarding outer space activities. The discussion began at the U.N. COPUOS in 2010. In June 2019, the 21 guidelines were finally adopted. The guidelines include international cooperation to promote and support the observation of the situation of orbiting objects, including space debris, for the purpose of preserving the space environment indefinitely, sharing data and forecasts on space weather, and announcing each country's space policy in accordance with international law. Some guidelines have failed to reach a consensus as the mitigation of space debris is often difficult to separate from space weapons tests. As plans for small satellites and Rendezvous and Proximity Operations have been projected for the future, it is expected that each countries' position on preserving the space environment will become more acute.

• Neurospine
• /
• v.15 no.4
• /
• pp.338-347
• /
• 2018

Objective: Patients with extradural spine tumors are at an increased risk for intraoperative cerebrospinal fluid (CSF) leaks and postoperative wound dehiscence due to radiotherapy and other comorbidities related to systemic cancer treatment. In this case series, we discuss our experience with the management of intraoperative durotomies and wound closure strategies for this complex surgical patient population. Methods: We reviewed our recent single-center experience with spine surgery for primarily extradural tumors, with attention to intraoperative durotomy occurrence and postoperative wound-related complications. Results: A total of 105 patients underwent tumor resection and spinal reconstruction with instrumented fusion for a multitude of pathologies. Twelve of the 105 patients (11.4%) reviewed had intraoperative durotomies. Of these, 3 underwent reoperation for a delayed complication, including 1 epidural hematoma, 1 retained drain, and 1 wound infection. Of the 93 uncomplicated index operations, there were a total of 9 reoperations: 2 for epidural hematoma, 3 for wound infection, 2 for wound dehiscence, and 2 for recurrent primary disease. One patient was readmitted for a delayed spinal fluid leak. The average length of stay for patients with and without intraoperative durotomy was 7.3 and 5.9 days, respectively, with a nonsignificant trend for an increased length of stay in the durotomy cases (p=0.098). Conclusion: Surgery for extradural tumor resections can be complicated by CSF leaks due to the proximity of the tumor to the dura. When encountered, a variety of strategies may be employed to minimize subsequent morbidity.