• Journal of Advanced Navigation Technology
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• v.16 no.5
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• pp.794-800
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• 2012

In this paper, we propose a scheme for improving not only the utilization of frequency bands in the guard channel scheme but also the dropping rate of cognitive radio user in the wireless cognitive radio-based cellular network. The proposed scheme enables cognitive radio users to utilize the guard channel for servicing only handoff calls in normal times, but cognitive radio users must vacate the frequency channel when handoff call appearing. At this time our scheme ensures their seamless services for cognitive radio users, by predicting handoff call's appearance by MMOSPRED (Multi-Media One Step Prediction) method and then reserving the demanded channels for spectrum handoff calls. Our simulations show that our scheme performs better than other schemes; GCS(Guard Channel Scheme) and a scheme without prediction in terms of cognitive users call's dropping rate and resource utilization efficiency.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.21 no.3
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• pp.168-176
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• 2011

Objectives: Hundreds of thousands of call center workers are wearing an acoustic device for their businesses, such as telemarketing and customer counseling, and the number of the workers are increasing sharply. Because call center workers always talk to dozens of customers over the headset, they would be placed under the state of a higher risk with their hearing ability. The purpose of this study is to investigate factors that affect the hearing thresholds for the call center workers. Methods: This study investigated hearing losses of 101 workers of 5 call centers in Korea by executing puretone audiometry and self-administered questionnaires. A cross table analysis was processed to compare gender differences between male and female. Male and female hearing thresholds were compared with the Students' t-test, and one-way ANOVA was conducted to observe the difference between non-occupational and occupational characteristics in 2, 3, 4, 6, and 8 kHz hearing thresholds for the female workers. Additionally, multiple regression analysis was conducted to find the factors that affect the 4 kHz hearing thresholds. Results and Conclusions: Male hearing thresholds were higher than those of female except for 8 kHz. In the group having an ear related disease, hearing threshold of male left ear was highly affected rather than that of female in 4 kHz. There were significant differences in the variables of alcohol drinking (2 kHz) and headset volume (8 kHz) in both ears. While this study does not show any significant factors that affect the hearing thresholds in the occupational characteristics, the gender and the previous ear related diseases, non-occupational characteristics, were found as the factors in 4 kHz. It is suggested that the more detailed survey be performed to identify the occupational factors that affect the hearing thresholds in the call center workers based on the result derived from this study.

• THE INTERNATIONAL COMMERCE & LAW REVIEW
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• v.47
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• pp.129-156
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• 2010

Since the 1970s, international construction employers have commonly requested first demand guarantees upon their contractors as a form of security for due performance of their works. Contractors prefer the greater protection offered by more traditional forms of security requiring presentation of an arbitral award or other evidence of the caller's entitlement to compensation. Many contractors nonetheless feel that they have no alternative but to provide these unconditional guarantees in order to compete. However, these unconditional first demand guarantees are controversial and have given rise to numerous disputes both in arbitration and litigation. Disputes arising from first demand guarantees can be broken down into a) applications to prevent a perceived fraudulent or otherwise unfair or improper calling of a guarantee, b) claims arising from such abusive calls and c) claims relating to the consequences of such calls even if the call itself may not be abusive as such. The contractors should carefully assess the risk of an abusive call being made bearing in mind the difficulties he may face in seeking to prevent such a call. He should also bear in mind the difficulties, delays and cost he is likely to encounter in seeking to recover any monies wrongfully called. One option would be to provide that the call can only be made once and to the extent that the employer's damages have been assessed or even incurred or even for the default to have been established by an arbitral tribunal or court. Another option would be to provide that any call be accompanied by a decision of a competent and impartial third party stating that the contractor is in breach. For example, such a requirement could be incorporated into a construction contract based on the FIDIC Conditions by submitting this decision to a Dispute Adjudication Board. Another option would be to provide for the "ICC Counter-Guarantee Scheme". In sum, there would appear to be room for compromise between the employer and the contractor in respect of first demand guarantees by conditioning the entitlement to call such guarantees to the determination of a competent and impartial third party.

• The Journal of the Korea Contents Association
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• v.7 no.3
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• pp.34-41
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• 2007

The presence service which provides user's presence information by subscription and notification is one of SIP(session initiation protocol) extension services, and it is used importantly in VoIP(Voice over IP) and Instant Messaging service. In this paper, we propose a new method in which users can combine and control presence service and call processing services in various ways by extending call processing language, and only changed parts of the presence information are published instead of full presence information document. Each user registers full presence information document with his own call processing script during the first publication to a presence server. The presence server executes these call processing scripts, so it can provide various services with combination of presence service and call processing services during the presence subscriptions and notifications. Afterwards, users publish only changed parts of the presence information and the presence server notify only these changed parts to watchers. Therefore the efficiency of the overall system can be improved. The performance of our proposed model is evaluated by experiments.

• Journal of Distribution Science
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• v.14 no.5
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• pp.91-96
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• 2016

Purpose - Although various studies have been conducted on the stress of service employees, there are still lack of studies regarding job stress and job satisfaction of call center workers. Especially there are quite few studies on the job stress according to employment type. This study focused on job stress and job satisfaction for call center employees and the correlation between the two factors and aimed to provide basic materials for seeking for the plans to reduce job stress and improve job satisfaction. Research design, data, and methodology - Frequency, percentage, and mean value were calculated through descriptive statistics in order to find out demographic characteristics, level of job stress, and job satisfaction. Differences in job stress according to employment type were calculated by using one-way ANOVA. Correlation between job stress and job satisfaction were identified through empirical analysis with Pearson's correlation coefficient. 150 materials were used for final analysis. The collected materials were analyzed to get statistics by using SPSS 20. Results - First, as for the job stress of call center workers, overall mean value was 2.54 in 4-point scales. Among the six sub-factors, job demands had the highest score, which was 2.67. Second, as for the job stress according to employment type, others showed higher score than mean value followed by contract job and full-time job in that order, in terms of job insecurity and organizational system. In terms of inappropriate remuneration, contract job showed higher score than mean value followed by others and full-time job. Third, as for the satisfaction with job, the mean value was 2.37 in 4-point scale and "very much satisfied" was only 3.3%. Lastly, in terms of job stress and job satisfaction, all sub-factors except for job demands showed significant correlation. The more job stress increased, the more job satisfaction decreased. Conclusions - First, as a result of analyzing job stress according to the employment type of call center workers, job stress increased more when the employment type was not full-time. Therefore, it was assumed that self-rescue efforts should be followed for effective employment management of call center business where contract employment takes most part as well as efforts to transfer them to full-time job. Second, decrease in job satisfaction of call center workers may affect the performance of an organization as well as service quality of the company providing the service. Therefore, various supports are required to decrease job stress and increase job satisfaction for call center workers through the expansion of rest area or break time. Third, I could recognize that there were lack of academic research on call center business in the whole service industry. Therefore, further research should be conducted more actively in the future. In particular, this study has special significance in the aspect that there were few studies on the job stress of call center workers according to employment type.

• International Journal of Safety
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• v.6 no.2
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• pp.43-48
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• 2007

We introduced the Excavation One Call System (EOCS) as a pilot system, in Seoul, Korea. The system utilizes the phone and internet to transfer information about digging underground and buried gas pipelines, although currently written forms are used in accordance with the City Gas Business Law. After one year, we evaluated the business model by surveying the excavators and the operators of the gas companies. This paper shows that the EOCS was more effective in preventing the buried gas pipelines from being damaged than the existing method that has to use due form. It also shows that the EOCS was more convenient and cost efficient than the present policies in place. We come to the conclusion that the EOCS should be extended nationwide and gradually include other subsurface facilities.

• Journal of the military operations research society of Korea
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• v.22 no.1
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• pp.30-42
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• 1996

This study deals with an optimal firecar location and allocation models under uncertain enemy attack at the airforce base. It allocates just one firecar on the runaway and the other firecars on the headquarter of firecar company in usual situation. It is possible for several facilities at the airforce base to be attacked simultaneously by missiles enemy air attacker, other things under uncertain enemy attack. We formulate two stochastic LP location-allocation models to deal with uncertainty. One model is to locate all firecars on one site like present situation. We generate a new firecar location with a weighted average method. We call this model "centralized allocation model". The other model is to distribute firecars on several possible sites. We call this model "distributed allcoation model". Finally, we compare two models with computer experimentations on 8 airforce bases.on 8 airforce bases.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.37 no.6
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• pp.1-11
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• 2000

In this paper, we propose a novel control signaling protocol that efficiently controls connection setup and increases the utilization of network resources. The proposed protocol, Separated Control Signaling Protocol(SCSP), separates bearer control from call control lot WDM optical networks. The main function of call control is to check the availability of network resources such as wavelengths and receivers at destination node. Bearer control is to reserve and assign wavelengths. The signaling architecture of this protocol consists of call controller and hearer controller The call controller handles call setup and release, activates the beater controller, and manages the status of call and bearer. The bearer controller reserves wavelengths, sets up bearer, tears down bearer. and notifies the status of beater to call controller. The state transition diagrams of each controller are designed. Using control messages and related primitives, the information flows for call setup and bearer setup, hearer teardown and call release, and reaction for setup failures are described to evaluate the performance. The simulation results show that the separated control signaling protocol is superior to conventional one in terms of call blocking probability and resource utilization.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.30A no.12
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• pp.10-17
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• 1993

In this paper, CCF(Call Control Function), functional entity for basic call processing in SSP(Service Switching Point), is designed and implemented. This functional entity can provide the IN(Intelligent Network) services which are included in CCITT CS-1(Capability Set-1), near-term process for IN Architecture. UIO(Unique Input Output) method, one of the thest sequence generation methods for the finite state machine, is used for the implementation test of this functional entity.

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 1986.04a
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• pp.113-118
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• 1986

Nowdays switching software designs are based on the concept of maximizing efficiency. This idea is to put through the most call, in the fastest time, using the fewest possible resources. So the memory usages are embossed one of the most important part to be considered in the switching software. This paper discusses the general concepts of switching software at first, then describes the switching data base from the view point of the access time, memory efficiency, and call processing environment.