• Proceedings of the Korean Operations and Management Science Society Conference
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• 2003.05a
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• pp.683-690
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• 2003

This purpose of this research is an attempt to measure and comparatively analyze the efficiencies and RTS(Returns to Scale) using panel data of OECD countries including Korea. In order to achieve this purpose, at first this study used efficient production frontier estimation combined with DEA for obtaining parameter estimates of a efficient production frontier. secondly using estimated results, measured R&D productivity and RTS(Returns to Scale) on all of the OECD countries. thirdly using time-series data related to R&D activity of korea, measured R&D productivity and RTS(Returns to Scale). Finally based on the results of R&D productivity and RTS(Returns to Scale) using efficient production frontier, some policy implications for enhancing the R&D competitiveness and the technological capabilities are discussed.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.250-250
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• 2010

The random telegraph signal (RTS) for the NOR flash cell scaling is investigated. An innovative method to suppress the RTS, based on the device engineering, is proposed. By optimizing the channel doping profile and using the high-k tunnel dielectric, it is confirmed from three-dimensional (3-D) simulation, that the $V_{th}$ amplitude, dueto RTS, is significantly suppressed, from approximately 0.5 to 0.07 V in the middle of the channel at 45 nm NOR Flash technology. From this result, it is expected that the proposed method to suppress the RTS amplitude is essential for further cell size scaling in Flash memory.

• Journal of KIISE:Information Networking
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• v.35 no.4
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• pp.326-336
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• 2008

Wireless sensor networks have been studied with two typical applications called event-driven and periodic monitoring. Although these applications have different core requirements, they have the same low latency requirement. However, main issue of the protocol in wireless sensor networks was focused on an energy efficiency, so it has not considered the latency problem. In this paper, we propose the RA-MAC, an energy efficient and low latency MAC protocol using a new channel access mechanism and the RTS Aggregation scheme for wireless sensor networks. Our simulation results show that the RA-MAC provides energy savings and latency reduction.

• Journal of Trauma and Injury
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• v.19 no.1
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• pp.35-40
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• 2006

Purpose: Injuries are the third leading cause of death in Korea. Isolated chest injury is not uncommon and shows high mortality and morbidity. Several scoring systems are used for triage and stratification for trauma patients, but no standard system is accepted. We aimed to analyze the accuracy of identification of isolated chest injury by using several scoring systems. Methods: We reviewed a total of 75 patients admitted with isolated chest injury between January 2005 and October 2005. Medical records were reviewed by using the Injury Severity Score (ISS), the Revised Trauma Score (RTS), and the Trauma and Injury Severity Score (TRISS). The scoring systems were compared by using statistics methods. Results: The overall predictive accuracy of the TRISS was 12.5%, 12.0% greater than those of the RTS and the ISS. By using the area under the receiver operating characteristic (AUROC) curve, the TRISS showed an excellent discriminative power (AUROC 0.931) compared to the ISS (AUROC 0.926) and the RTS (AUROC 0.872). Conclusion: Compared with the RTS and the ISS, the TRISS is an easily applied tool with excellent prognostic abilities for isolated chest trauma patients. However, the TRISS, the ISS, and the RTS showed high specificity and low sensitivity, so another scoring system is required for triage and stratification of isolated chest injury patients.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.45 no.6
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• pp.33-44
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• 2008

Multipath routing protocols with load balance, fault tolerance, aggregated bandwidth in Ad-hoc Networks provide improved throughput and reliable route as compared with singlepath routing protocols. However, multipath routing protocols have not been explored thoroughly in the domain of overhead in Ad-hoc Networks. In this paper, we analyze and compare on-demand singlepath and multipath routing with IEEE 802.11 DCF in terms of Routing overhead and MAC overhead. The results reveals that in comparison with singlepath routing protocol, multipath routing mechanism creates more overheads but provides better performance in congestion and capacity provided that the route length is within a certain upper bound which is derivable. The analytical results are further confirmed by simulation.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.3A
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• pp.304-310
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• 2006

This paper evaluates the performance of three types of data delivery mechanisms in clustered sensor networks, as a basic research to develop an energy efficient topology management scheme. In the first mechanism, one node per cluster(clusterhead) turns on its radio(or wakes up) to transmit and receive RTS/CTS/DATA/ACK messages, but in the second one, k nodes per cluster wake up and participate in the message exchange. In the last mechanism, clusterheads turn on the radio to exchange RTS/CTS messages, and if a clusterhead receives RTS containing its cluster m as a destination, it makes k nodes in the cluster hun on the radio to receive DATA and transmit ACK. Through simulation, we show the energy consumption of the three types of data delivery mechanisms as functions of the number of active nodes per cluster, offered load, and packet loss probability.

• Smart Structures and Systems
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• v.12 no.3_4
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• pp.251-269
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• 2013

Measurement of deflections of certain bridges is usually hampered by corruption of the GPS signal by multipath associated with passing vehicles, resulting to unrealistically large apparent displacements. Field data from the Gorgopotamos train bridge in Greece and systematic experiments revealed that such bias is due to superimposition of two major effects, (i) changes in the geometry of satellites because of partial masking of certain satellites by the passing vehicles (this effect can be faced with solutions excluding satellites that get temporarily blocked by passing vehicles) and (ii) dynamic multipath caused from reflection of satellite signals on the passing trains, a high frequency multipath effect, different from the static multipath. Dynamic multipath seems to have rather irregular amplitude, depending on the geometry of measured satellites, but a typical pattern, mainly consisting of a baseline offset, wide base peaks correlating with the sequence of main reflective surfaces of the vehicles passing next to the antenna. In cases of limited corruption of GPS signal by dynamic multipath, corresponding to scale distortion of the short-period component of the GPS waveforms, we propose an algorithm which permits to reconstruct the waveform of bridge deflections using a weak fusion of GPS and RTS data, based on the complementary characteristics of the two instruments. By application of the proposed algorithm we managed to extract semi-static and dynamic displacements and oscillation frequencies of a historical railway bridge under train loading by using noisy GPS and RTS recordings. The combination of GPS and RTS is possible because these two sensors can be fully collocated and have complementary characteristics, with RTS and GPS focusing on the long- and short-period characteristics of the displacement, respectively.

• Journal of East-West Nursing Research
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• v.28 no.1
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• pp.10-20
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• 2022

Purpose: We compared the Korean Triage and Acuity Scale (KTAS), Injury Severity Score (ISS), and Revised Trauma Score (RTS) determined the validity of KTAS for classifying trauma patients. Methods: A retrospective chart review of 10,865 trauma patients (aged ≥15 years) who visited a single regional trauma and emergency medical center from January 1, 2016, to December 31, 2020, was conducted. Data were collected from the Korean Trauma Data Bank. Based on KTAS classification, the rates of intensive care unit admission, surgery and intervention, transfusion, emergency room (ER) and hospital mortality, and ER stay time were investigated. Data were analyzed using Chi-square test, Pearson's correlation coefficient, receiver operating characteristic curve, and area under the ROC curve. Results: In the KTAS, severe trauma patients (ISS ≥16) were classified as Level 1 (79.6%), 2 (44.8%), 3 (15.5%), 4 (4.0%) and 5 (7.6%). The following were the predictive powers of KTAS, ISS, and RTS for different parameters: surgery and intervention rate, KTAS (.71), ISS (.70), and RTS (.63); transfusion rate within 4h, KTAS (.82), ISS (.82), and RTS (.74); ER stay time within 90 min, KTAS (.72), ISS (.62), and RTS (.56); and ER mortality, KTAS (.84), ISS (.72), and RTS (.88). These findings were statistically significant (p<.001). The sensitivity and specificity of KTAS for trauma patients were .88 (.87~.90), and .38 (.37~.39), respectively. Conclusion: KTAS is a useful classification system that can predict the clinical outcomes of patients with trauma, and effectively triage acutely ill trauma patients, thus provide appropriate treatment.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.49 no.3
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• pp.19-25
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• 2012

Underwater sensor networks (UWSNs) employ acoustic channels for communications. One of the main characteristics of the underwater acoustic channel is long propagation delay. Previously proposed MAC (medium access control) protocols for wireless sensor networks cannot be directly used in UWSNs due to the long propagation delay. The long propagation delay and uneven nodes deployments cause spatial fairness in UWSNs. Therefore, a new MAC protocol for UWSNs needs to be developed to provide efficient communications. In this paper, we propose an efficient MAC protocol in order to alleviate the fairness problem. In the proposed scheme, when a node receives a RTS packet, it does not immediately send back but delays a CTS packet. The node collects several RTS packets from source nodes during the delay time. It chooses one of the RTS packets based on the queue status information. And then, it sends a CTS packet to the source node which sent the chosen RTS packet. The performance of the proposed scheme is investigated via simulation. Simulation results show that our scheme is effective and alleviates the fairness problem.

• Proceedings of the SAREK Conference
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• 2006.06a
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• pp.525-530
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• 2006