• Proceedings of the KIEE Conference
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• 2005.05a
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• pp.221-223
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• 2005

In a CDMA system, the capacity is variable and mainly depends on multiple access interference. The multiple access interference has a deep relationship with transmitted or received power. The capacity of CDMA2000 1x system is considered to be limited by the forward link capacity. Different rate data traffic requires different transmitted power and rate controlling enables the system utilize radio resource more efficiently. A very simple rate control algorithm fer data calls in CDMA2000 1x system is proposed. In the proposed algorithm, by monitoring the total transmit power, we can simply adjust data rate to channel conditions and efficiently use radio resources. The proposed algorithm is easy to implement in power controlled CDMA systems.

• MALSORI
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• no.52
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• pp.161-169
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• 2004

This paper describes the automated call routing for train ticket reservation aid system based on speech recognition. We focus on the task of automatically routing telephone calls based on user's fluently spoken response instead of touch tone menus in an interactive voice response system. Vector-based call routing algorithm is investigated and mapping table for key term is suggested. Korail database collected by KT is used for call routing experiment. We evaluate call-classification experiments for transcribed text from Korail database. In case of small training data, an average call routing error reduction rate of 14% is observed when mapping table is used.

• Proceedings of the KSR Conference
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• 2011.10a
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• pp.2775-2781
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• 2011

Urban Transit Train Radio is Radio Communication system that is used official business as leading motive for train safety running among the train crew and the central control center and drive-caring-chamber on main line and branch line. This system is operated that organizes talking path on handset of terminal after the train crew receives audio and understands call voice on speaker of terminal at calling the train of the central control center. When the central control center calls the specific train uses all call radio form, the train crew doesn't recognize the call cause the train situation, noise and action as train control. So there is a delay response cause reset call at the central control center. This research discusses the management of subway radio system and describes the call the train system that recognize train call number of all-call used between the central control center and the train crew.

• Proceedings of the KIEE Conference
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• 1987.07b
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• pp.965-968
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• 1987

Conventional major electronic switching systems based on stored program control employ a Von Neumann styled control processor. It has strict limitations such that it essentially lacks concurrency in executing instructions, which have brought the software bottleneck problem, and the capabilities of call processing are restricted by expanding system's capacity. In this paper, a new architecture of call control processor based on the data flow system is proposed, aiming at fundamental resolution for these limitations. The processor has a number of advantages in such as expansibility of system's capacity, parallel processing of calls, and so on.

• Proceedings of the KSR Conference
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• 2009.05b
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• pp.285-291
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• 2009

If an urgent situation, such as a stroke, faint, heart attack, happens in a lavatory, it is hard to recognize and perform an immediate emergency treatment unless the patient inside of the lavatory calls for help. If a system that can detect an emergency in a lavatory and report to the relevant personnel is developed, it would be an excellent installation case demonstrating how a train is nicely designed to take care passenger's safety. In this paper, we showed a design of lavatory emergency detection system (LEDS) that detects an urgent situation in a lavatory by using sensors and timers and reports to proper personnel. This system can be installed not only on a train but also in a building where visual monitoring is not possible.

• The Journal of the Korea institute of electronic communication sciences
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• v.15 no.5
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• pp.857-864
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• 2020

The multi-functional VoIP phone supports the Ethernet protocol in the TIPS(: Tactical IP Switch), which is one of the sub-systems of the tactical information and communication system (TICN). It provides secured voice / video calls in conjunction with VoIP exchanges and supports differential services such as multi-party calls and command functions. In this paper, improving methods have been proposed to reduce power supply defects in the field of multi-functional VoIP phones. The power supply part was improved by applying TVS of the output voltage inlet of the dedicated adapter of the multi-functional VoIP phone, TVS of the PoE module input, adding blocking diodes, and adding DC / DC converters behind the poly-switch. Also, functional and environmental tests were performed to verify the validity of the proposed methods.

• Journal of Broadcast Engineering
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• v.14 no.2
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• pp.178-188
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• 2009

In this paper, we propose the method which provides efficient sub-channel allocation for handoff and new call supporting multi-media service in AMC-based OFDMA system. Firstly, we apply the multi-band method which provides different AMC method according to the location of user terminals. Also, in OFDMA system environment that a base station has a lot of sub-channels, we adopt the sub-channel allocation scheme that provides a higher priority to handoff call and real-time service about handoff and new calls with multi-meida service. The simulation results show that the proposed scheme plays a role in increasing the number of new and handoff calls meeting the required blocking rate.

• Smart Media Journal
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• v.5 no.4
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• pp.131-137
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• 2016

Since the phenomenon that the consumers slip important calls since they do not know the receiving information of the smart phone in spaces which smart phones can not be carried, the development of technology to solve this problem is urgent and the cases of burglary and losses of smart phones during hobby and recreation life are increasing and especially since burglary behaviors are occurring much in places such as bathing resort, swimming pool, Korean dry sauna, sauna and spa etc, the schemes to protect smart phones during hobbies and recreation life is needed. Since the smart watch, the conventional wearable device are high price machines and due to the burden about A/S costs for the damage or failure of the machine during exercise, hobbies and recreation activities, the burden about the use is high, development of products which can reduce such burden and emphasize the usefulness is urgent and in order to solve this problem, the added value and psychological repercussion effect will be very high in areas of smart phone users and utilizing them by developing the system which can know if the smart phone has received calls at least in places where smart phones can not be carried.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.10 no.11
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• pp.1978-1982
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• 2006

The EPIRB overcame the limitations of the conventional marine communication systems, the false distress calls by EPIRB systems internationally account for about 94 percent of the total calls because of the different usages of EPIRB systems with manufacturers, users' errors, and systems' faults. To resolve these problems, international bodies and manufacturers are developing many measures to reduce those error emissions. In conventional systems, the distress call was sent immediately after the EPIRB is removed from the automatic release system. Taking into account the properties of the system, however manufacturers improved the operation so that the distress call is sent only when the EPIRB is released and then immersed into water. In spite of these efforts, the error emissions have not significantly reduced. In this study, the domestic and international technical regulations and standards for the COSPAS-SARSAT and satellite EPIRB systems were reviewed, and a bridge-type water detection sensor was developed to minimize the error emission from EPIRB.

• Clinical and Experimental Emergency Medicine
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• v.5 no.4
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• pp.272-277
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• 2018

Objective While the effect of typhoons on emergency medicine has been evaluated, data are scarce on their effects on the emergency medical service (EMS). This study evaluated the effect of typhoons on EMS patients and performance. Methods The study period was January 2010 to December 2012. Meteorological data regarding typhoons were provided by the Korean Meteorological Administration. EMS data were retrieved from the EMS database of the national emergency management agency. The database includes ambulance run sheets, which contain clinical and operational data. In this case-crossover study, the cases and controls were EMS calls on the day of typhoon warnings and calls one week prior to the typhoon warnings, respectively. Results During the study period, 11 typhoons affected Korea. A total of 14,521 cases were selected for analysis. Overall, there were no obvious differences between the case and control groups. However, there were statistically significant differences in age, place, and time requests. There were fewer patients between 0 and 15 years of age (P=0.01) and more unconscious patients (P=0.01) in the case group. The EMS operational performance, as measured by the times elapsed between call to start, call to field, and call to hospital did not differ significantly. There was also no significant difference in the time from hospital arrival between the cases (28.67, standard deviation 16.37) and controls (28.97, standard deviation 28.91) (P=0.39). Conclusion Typhoons did not significantly affect the EMS system in this study. Further study is necessary to understand the reasons for this finding.