• Journal of Advanced Navigation Technology
• /
• v.7 no.2
• /
• pp.149-155
• /
• 2003

This paper generally relates to the field of wireless local area networks(WLANs), and more particularly, to AP selection and association methods for the performance of a station. In these days, IEEE 802.11 Wireless LAN network is widely deployed and used as an emerging service to connect high-speed Internet in the public wireless environment. But, if there are many users in hot spot area, they suffer a severe decrease of performance. Thus it needs an association and access control mechanism especially when it is used in the public environment. In this paper, we suggest a selection and association method using Beacon or Probe Response frames based IEEE 802.11. Station selects AP using the information of the capacity area in a Beacon or a Probe Response frame. According to the present paper, an association method for a public WLAN service, which includes a WLAN user terminal and an AP for relaying WLAN communications to and from the user terminal, includes the steps of the user terminal asking the AP's states for access to a radio channel; and the station selects and associates with the AP. According to the above-described selection in a high speed wireless Internet service based on public WLAN technologies that are currently in operations. Further, it is possible to improve the efficiency of network management.

• The KIPS Transactions:PartD
• /
• v.12D no.3 s.99
• /
• pp.461-470
• /
• 2005

This paper suggests a new policy for consolidating a company's profits by segregating the clients using the contents service and allocating the media server's resources distinctively by clusters using the cluster analysis method of CRM, which is mainly applied to marketing. In this case, CRM refers to the strategy of consolidating a company's profits by efficiently managing the clients, providing them with a more effective, personalized service, and managing the resources more effectively. For the realization of a new service policy, this paper analyzes the level of contribution $vis-\acute{a}-vis$ the clients' service pattern (total number of visits to the homepage, service type, service usage period, total payment, average service period, service charge per homepage visit) and profits through the cluster analysis of clients' data applying the K-Means Method. Clients were grouped into 4 clusters according to the contribution level in terms of profits. Likewise, the CRFA (Client Request Filtering algorithm) was suggested per cluster to allocate media server resources. CRFA issues approval within the resource limit of the cluster where the client belongs. In addition, to evaluate the efficiency of CRFA within the Client/Server environment the acceptance rate per class was determined, and an evaluation experiment on network traffic was conducted before and after applying CRFA. The results of the experiments showed that the application of CRFA led to the decrease in network expenses and growth of the acceptance rate of clients belonging to the cluster as well as the significant increase in the profits of the company.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.29 no.7B
• /
• pp.685-696
• /
• 2004

Real-time multimedia applications that require large amount of bandwidth need resource reservation before starting service for providing the QoS(i.e., Quality of Service). To reserve resources in advance, each reservation request has to notify its expectation on the required amount of resources and service duration. Using this information, a resource manager can schedule advance reservations. However, most existing resource management systems are adopting straightforward call admission control process (i.e., only immediate reservation) by checking currently available resources without considering the service duration. Hence, the resource management system that supports advance reservation has to manage confliction caused by indefinite service duration of immediate reservation. Even though the separation of resource pool according to type of reservation can prevent the confliction, it causes low resource utilization. In this paper, we propose an effective resource management scheme that supports both immediate and advance reservations by sharing resources dynamically. Using network cost function, the proposed scheme determines and adaptively adjusts resource boundary according to the confliction rate by varying weight parameters. And also, we define user utility function to quantify user satisfaction based on how well the reserved resource is guaranteed during service time. Simulation results using NS-2 network simulator show that the proposed scheme can achieve better resource utilization with preferable QoS than other schemes like static resource partitioning.

• Journal of the Institute of Electronics and Information Engineers
• /
• v.50 no.1
• /
• pp.34-45
• /
• 2013

Recently, world-wide research activities on new network architectures and protocols are being actively progressed. Furthermore, research activities on testbed and related technologies for supporting those activities are being actively performed. In domestic study, research on the OpenFlow protocol based future Internet testbed implementation and research on its virtualization for supporting independent research experiments are being performed at the same time. The network virtualization is a technology which maximizes the testbed utilization without interfering each other for the individual research when many researchers share the testbed. In this paper, we implemented a Enhanced FlowVisor by extending basic FlowVisor by adding QoS functions which are admission control and minimum bandwidth guarantee. On the testbed, we performed a real-time video streaming experiment for verifying the performance of the Enhnaced FlowVisor on the OpenFlow protocol based future internet testbed. The result shows that the Enhanced FlowVisor can provide reliable and stable QoS to the individual researches without disturbing each other traffic on virtualized networks of the future Internet testbed.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.28 no.6B
• /
• pp.588-603
• /
• 2003

In this paper, we propose an Aggregate Three Color Marker without per flow management which is required for an Edge router to improve End-to-End QoS of Assured Service in DiffServ. Proposed Aggregate Three Color Marker is used with the Adaptive RIO-DC scheme to achieve the minimum rate guarantee without per flow management. Assuming that the admission control for Assured Service has been performed, proposed Aggregate Three Color Marker measures incoming In-profile traffic rate at the output link of an edge router using a token-bucket with a token rate equal to the sum of contracted rates of admitted flows passing the edge router. If there are token losses from the token bucket, out-of-profile packets are promoted to Yellow packets within the aggregate traffic profile. And yellow packets are demoted to out-of-profile packets at the input link to an Edge router fer the purpose of fairness maintenance. In-profile packets and Yellow packets are processed identically at the RIO-DC buffer management scheme in our proposed method. Simulation results show that through using proposed Aggregate Three Color Marker with the Adaptive RIO-DC scheme, the minimum rate guarantee for Assured Service can be achieved without per flow management at multiple DiffServ domains.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.38A no.1
• /
• pp.68-78
• /
• 2013

In this paper, we propose an early spectrum sensing(ESS) as an advance preparation for radio-access trial, which enables multi-mode terminals to access the most appropriate radio-access system in a cloud-conceptual base station system where multiple radio access technologies(RATs) coexist. Prior to a random access to one of RATs, a multi-mode terminal conducts a spectrum sensing over entire frequency bands of whole RATs, then select the RAT with the lowest sensing power, that is likely to have the most available spectrum. Thus, an access failure caused by that the selected RAT has no available radio spectrum could be avoidable in advance. In computer simulation, we consider as various RATs as possible. First, circuit and packet systems are taken into consideration. In addition, the packet systems are classified according to the feasibility of carrier aggregation(CA). In case of terminal, three modes are considered with circuit-only, packet-only, and multi-mode. Subsequently, packet traffic is classified into real-time and non-real-time traffic with three different tolerable delay levels. The simulation includes a call process starting with a call generation and ending up with a resource allocation reflecting individual user's QoS requirements and evaluates the proposed scheme in terms of the successful access probability, system access time, system balancing factor and packet loss probability.

• Korean Journal of Head & Neck Oncology
• /
• v.12 no.2
• /
• pp.217-223
• /
• 1996

A retrospective analysis was performed to assess the relationship between the treatment modalities and treatment results in patients with adenoid cystic carcinoma of the maxillary sinus. From Feb. 1977 to March 1994, 10 patients with the disease were treated at the Department of Radiation Oncology, Yonsei Cancer Center, Yonsei University College of Medicine. Six men and 4 women were presented with median age of 57 years. According to AJCC TNM system, all patients except one had advanced T3 and T4 disease. Only one patient had the regional metastasis to lymph node but none of them had hematogenous metastasis on initial admission. One patient(Group 1) was treated with surgery alone, 3 patients(Group 2) were treated with definitive radiotherapy and 6 patients(Group 3) were treated with combination of surgery and radiotherapy. One patient who was treated with surgery alone had experienced a locoregional recurrence 9 months later and 3 patients who were treated with radiation therapy alone had PRs(partial response) followed by the subsequent progression of the local disease. Whereas all patients who were treated with combination of surgery and radiation therapy had CRs(complete response). Among them, only one patient was recurred in the primary site, who was salvaged by reoperation and reirradiation therapy. In conclusion, combination of surgery and radiotherapy resulted in the best treatment modality for adenoid cystic carcinoma of the maxillary sinus. Improved radiotherapy technique and development of multimodality treatment are needed to improve the local control and the survival rate in patients with advanced adenoid cystic carcinoma of the maxillary sinus.

• The Journal of Korean Physical Therapy
• /
• v.15 no.4
• /
• pp.151-179
• /
• 2003

The purpose of this study was to examine the influence of total knee replacement to arthritis patients in pain intensity and functional impairment. For this study, over 50-year-old 30 patients who had osteoarthritis and 69 patients who got total knee replacement at the one of the departments of orthopedics in Daegu were interviewed from June, 2002 to March, 2003. The results of this study were as follows : First, pain intensity was decreased to experimental group after operation than control group(P<.01) And the presence of crepitation was also decreased to them(P<.05). On the other hand there's no significant difference was noted in the presence of stiffness, degree of flexion contracture and extension contracture between two groups. Second, over 91 days group after operation and visitor's group of physiotherapy unit were better than others in Level of knee function(P<.01). Third, over 91 days group after operation and visitor's group of physiotherapy unit were higher than others in Barthel Index of knee function(P<.01). Forth, over 91 days group after operation and visitor's group of physiotherapy unit were higher than others in Level of IADL(P<.05). Fifth, over 91 days group after operation and visitor‘s group of physiotherapy unit were higher than others in Katz Index of knee function(P<.01). Sixth, although Old Ages' Activity Index seemed to get better as time goes by, there's no statistical difference. Seventh, over 91 days group after operation and visitor's group of physiotherapy unit were higher than admission group and under 30 days group after operation in Social Activity Index(P<.05). Eighth, the function of the knee was connected with the abilities in the activity of the old and the social skill. The Barthel index was connected with the function of the knee joint and the activities of the old and Katz index. IADL function was connected with the activities of the old and the social activity. The Katz index was connected with the Barthel index. The activity of the old was connected with the Barthel index, the functional score of the knee joint andthe IADL score. The ability of social skill was connected with the activity of the old, IADL score and the function of the knee.

• Journal of Korean Academy of Nursing
• /
• v.29 no.4
• /
• pp.743-754
• /
• 1999

The purpose of this descriptive study was to identify the homecare needs of patients with cancer and to provide a basis of interventions. One hundred and two patients at one general hospital in Gyeongnam responded to a questionnaire developed on the basis of care needs perceived by nurses caring for hospitalized patients with cancer. The questionnaire was a Likert type 5 point scale with 56 items on five need categories ; 1) informational 2) physical care : 3) emotional care 4) socioeconomic care and 5) special care needs. Internal consistency of this questionnaire was Cronbach's $\alpha$＝.9101 for total items. The data was collected from March 1st to May 31th, 1998, by two graduate nurses. In the data analysis, mean & standard deviation were calculated to identify the degree of care need of each item, and the t-test & ANOVA were done to determine the effects of patients' demographic background on their care needs. The findings are summarized as follows ; 1) The mean score of total of need items was 3.048. Of the four need categories the highest score was informational at 3.4, followed by emotional care, 3.063, physical care, 2.623, and socioeconomic care, 2.599. 2) In the informational need category there were four subcategories with 19 items. Medication and pain control had the highest score, 3.755 ; second was diet and exercise, 3.613 ; third was disease and treatment process, 3.337 ; and last was personal hygiene and infection prevention at 2.687. 3) In the physical care need category there was nine items, IV infusion for nutrition and management of treatment complication was above 3.2 points and the remaining items were in the 2.847-2.070 score ranges. 4) In the emotional care need category there were seven items. The highest need was in support for relationships with health personnel, 3.673. The need for support of religions beliefs and support for having a religion were low at about 2 points. 5) In the socioeconomic care need category there were six items. Support for medical insurance expansion and financial support were above 3 points. Legal support and support for caring of children were low in the care needs. 6) In the special care need category the there were 15 items. Informational need about immunization and informational need about effects of disease on growth and development were high, above 4.1 points. Need for decubitus care and prevention, sitz bath and incontinence care were low, below 2 points. 7) There were significant differences in degree of care need according to admission rate, education level, marital status, religion and caregiver's religion. In conclusion, homecare needs perceived by hospitalized patient's with cancer was moderate, but informational need was higher than direct care need, leading to the conclusion that the provision of sufficient information to patients with cancer at discharge is needed. Nursing interventions should be developed considering the patient's background.

• Pediatric Infection and Vaccine
• /
• v.7 no.2
• /
• pp.250-256
• /
• 2000

The incidence of tuberculosis has been decreased, and especially the incidence of severe complicated tuberculosis has been markedly decreased as the result of widely used BCG vaccines. But tuberculosis is still an important community accquired infectiouse disease in the world despite continued worldwide efforts to control the disease. Miliary tuberculosis, the most serious complicated tuberculosis, can be occurred by lymphohematogenous dissemination of tuberculosis, and intracranial tuberculoma with or without tuberculosis meningitis can be developed in case of miliary tuberculosis. In general, serious tuberculosis infections such as miliary tuberculosis and CNS tuberculosis are developed especially in young infants and children in cases of delayed diagnosis and treatment despite receiving BCG vaccination, and usually those patients have contact sources. Intrcranial tuberculoma in children are usually found near infratentorial site at the base of cerebellum, and clinically symptoms and signs of increased intracranial pressure developed before treatment. Serial brain CT or MRI is a good non-invasive diagnostic modality of intracranial tuberculoma. Although surgical intervention was initially advocated as the mainstay of intracranial tuberculoma therapy, but many recent clinical studies indicate that intracranial tuberculoma can be cured with medical treatment alone. We experienced a case of 3 months old male patient, who was diagnosed as having miliary tuberculosis associated with multiple intracranial tuberculoma. He received BCG vaccination at 4 weeks after birth, and his father was confirmed as active pulmonary tuberculosis patient after this patient's admission. We report this case with a review of related literatures.