• Journal of Information Technology Applications and Management
• /
• v.14 no.3
• /
• pp.169-178
• /
• 2007

The next generation mobile multimedia network is expected to provide higher-rate multimedia communication services to versatile mobile terminals moving in even higher speed. For achieving more efficient reusability of scarce radio resources and thereby accommodating more user population in this network, the smaller cell such as micro or pico cell structure is used. More efficient and faster hand-over schemes are necessary to prevent the degradation of QoS of multimedia services caused by hand-over processing delay and packet loss during frequent hand-over. This paper proposes a faster and more effective hand-over scheme for high-rate multimedia services in the future mobile multimedia networks. by utilizing the GPS information on the position of the mobile terminal and its estimated moving directions. The simulation results show that our proposed method provides a better performance than the conventional method.

• Clinics in Shoulder and Elbow
• /
• v.27 no.1
• /
• pp.32-38
• /
• 2024

Background: Open reduction and internal fixation (ORIF) with a locking plate is a popular surgical treatment for proximal humeral fractures (PHF). This study aimed to assess the occurrence of complications in elderly patients with PHF treated surgically using ORIF with a locking plate and to investigate the potential differences between patients treated by shoulder surgeons and non-shoulder surgeons. Methods: A retrospective study was conducted using a single-center database to identify patients aged ≥70 years who underwent ORIF for PHF between January 1, 2011, and December 31, 2021. Data on the Neer classification, follow-up, occurrence of avascular necrosis of the humeral head, implant failure, and revision surgery were also collected. Statistical analyses were performed to calculate the overall frequency of complications according to the Neer classification. Results: The rates of implant failure, avascular osteonecrosis, and revision surgery were 15.7%, 4.8%, and 15.7%, respectively. Complications were more common in patients with Neer three- and four-part fractures. Although the difference between surgeries performed by shoulder surgeons and non-shoulder surgeons did not reach statistical significance, the rate of complications and the need for revision surgery were nearly two-fold higher in the latter group. Conclusions: PHF are highly prevalent in the elderly population. However, the ORIF surgical approach, as demonstrated in this study, is associated with a considerable rate of complications. Surgeries performed by non-shoulder surgeons had a higher rate of complications and a more frequent need for revision surgery. Future studies comparing surgical treatments and their respective complication rates are crucial to determine the optimal therapeutic options. Level of evidence: III.

• Elastomers and Composites
• /
• v.59 no.2
• /
• pp.73-81
• /
• 2024

In the field of electronic components, the potting material, which is a part of the electronic circuit package, plays a significant role in protecting circuits from the external environment and reducing signal interference among electronic devices during operation. This significantly affects the reliability of the components. Therefore, the accurate prediction and assessment of the lifespan of a material are of paramount importance in the electronics industry. We conducted an accelerated thermal aging evaluation using the Arrhenius technique on elastic potting material developed in-house, focusing on its insulation, waterproofing, and contraction properties. Through a comprehensive analysis of these properties and their interrelations, we confirmed the primary factors influencing molding material failure, as increased hardness is related to aggregation, adhesion, and post-hardening or thermal-aging-induced contraction. Furthermore, when plotting failure times against temperature, we observed that the hardness, adhesive strength, and water absorption rate were the predominant factors up to 120 ℃. Beyond this temperature, the tensile properties were the primary contributing factors. In contrast, the dielectric constant and loss tangent, which are vital for reducing signal interference in electric devices, exhibited positive changes(decreases) with aging and could be excluded as failure factors. Our findings establish valuable correlations between physical properties and techniques for the accurate prediction of failure time, with broad implications for future product lifespans. This study is particularly advantageous for advancing elastic potting materials to satisfy the stringent requirements of reliable environments.

• Proceedings of the Korean Society of Medical Physics Conference
• /
• 2004.11a
• /
• pp.158-161
• /
• 2004

In order for better management of a medical linear accelerator, the records of the operational failures of Varian CL2100C over ten years were analyzed. The failures were classified according to the involved functional subunits and each class was rated into three levels depending on operational conditions. The relationship between the failure rate and working ratio was investigated. Among the recorded failures ( total 587 failures), the most frequent failure, which was 20% of the total. was observed in the parts related to the collimation system including monitor chamber. Regrading to the operational conditions, the 2nd level of failures, that temporally interrupted treatments, was the most frequent. The 3rd level of failures, that interrupted treatment for more than several hours, was mostly caused by the accelerating subunit. The average life-time of a Klystron and Thyratron became shorter as the working ratio increased, which was 42 and 83% of the expected values, respectively. Recording equipment problems and failures in detail over a long period of time can provide a good knowledge of equipment function as well as the capability to forecast future failure. More rigorous equipment maintenance is required for old medical linear accelerator to avoid the serious failure in advance, and improve the patient treatment quality.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.27 no.1
• /
• pp.61-69
• /
• 2014

In this paper, we have researched semiconductor optical filters to solve the problem of the high failure rate that are recognize bad of financial account, jam of financial account and the ATM service interruption due to failure of accurate location information among the operation of the ATM (automatic teller machine) systems. A semiconductor optical filters that have high resolution and less diffuse, high transmittance are able to detect the information of financial account surface accurately. Therefore, it is a stable filter that is able to minimize the incidence of disability. In this paper, we drew the determinants by element for implement an excellent semiconductor optical filters. Based on this, we had to be able to implement the semiconductor optical filter that is able to be mounted on the actual ATM system through future studies.

• Journal of Ship and Ocean Technology
• /
• v.2 no.1
• /
• pp.58-70
• /
• 1998

Many bulk carrier losses have been reported of late, and one of the possible causes of such casualties is thought to be the structural failure of aging hulls in rough weather. Clearly, in such cases, vessels that start out belong adequate somehow become marginal later in life. Fatigue and corrosion related potential problems may be the most important factors affecting such age related vessel damage. With respect to fatigue, extensive studies have been done worldwide both experimentally and theoretically, and the results have been applied to some extent. However, in the case of corrosion effects, additional research is still needed to better understand, clarify and address the various strength uncertainties and their effects on structural behavior. This paper develops a probabilistic corrosion rate estimation model for the longitudinal strength members of bulk carriers. The model is based on available statistical data for corrosion of existing bulk carriers. The corrosion data collected are documented for future use.

• The Korean Journal of Gastroenterology
• /
• v.72 no.5
• /
• pp.237-244
• /
• 2018

While the prevalence of Helicobacter pylori (H. pylori) infection is decreasing in Korea, the incidence of gastric cancer remains high, emphasizing the importance of H. pylori eradication. A new treatment strategy is needed as the eradication rate with standard triple therapy, which is currently the standard first-line regimen for H. pylori infection, has decreased below the optimum level. The major cause of eradication failure is increased antibiotic resistance. Sequential, concurrent, and hybrid therapies that include clarithromycin produce higher eradication rates than conventional standard triple therapy. However, the effectiveness of these treatments is limited in regions where the resistance rate to various antibiotics is high. Bismuth quadruple therapy is another alternative therapy, but again the eradication rate is not sufficiently high. Tailored therapy based on individual characteristics, including antibiotic susceptibility, may be ideal, but there are several limitations for clinical application and further research is needed. New potassium-competitive acid blocker-based therapies could emerge as effective alternatives in the near future. A consensus is needed to establish a strategy for applying new eradication therapies in Korea.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.12 no.9
• /
• pp.1666-1674
• /
• 2008

In this paper, various forms of technical methods as well as comparison analysis on constructing optical subscriber network were studied to find the most economical installation method in the future. Comparison analysis has been focused on the three popular types of optical subscriber networks in Korea, such as VDSL2, Ethernet-LAN and FTTH-R. A study is conducted on the initial installation investment per subscriber, equipment failure rate as well as power consumption per subscriber. As a results, FTTH-R network will be the most economical method in the future, but a gradual switch which undergoes a UTP-fiber hybrid method as the midway process is preferable in considering the existing installed copper UTP subscriber cables.

• Journal of Korean Neurosurgical Society
• /
• v.62 no.3
• /
• pp.344-352
• /
• 2019

Epilepsy is one of the major chronic neurological diseases affecting many patients. Resection surgery is the most effective therapy for medically intractable epilepsy, but it is not feasible in all patients. Vagus nerve stimulation (VNS) is an adjunctive neuromodulation therapy that was approved in 1997 for the alleviation of seizures; however, efforts to control epilepsy by stimulating the vagus nerve have been studied for over 100 years. Although its exact mechanism is still under investigation, VNS is thought to affect various brain areas. Hence, VNS has a wide indication for various intractable epileptic syndromes and epilepsy-related comorbidities. Moreover, recent studies have shown anti-inflammatory effects of VNS, and the indication is expanding beyond epilepsy to rheumatoid arthritis, chronic headaches, and depression. VNS yields a more than 50% reduction in seizures in approximately 60% of recipients, with an increase in reduction rates as the follow-up duration increases. The complication rate of VNS is 3-6%, and infection is the most important complication to consider. However, revision surgery was reported to be feasible and safe with appropriate measures. Recently, noninvasive VNS (nVNS) has been introduced, which can be performed transcutaneously without implantation surgery. Although more clinical trials are being conducted, nVNS can reduce the risk of infection and subsequent device failure. In conclusion, VNS has been demonstrated to be beneficial and effective in the treatment of epilepsy and various diseases, and more development is expected in the future.

• Membrane Journal
• /
• v.33 no.2
• /
• pp.61-69
• /
• 2023

The technical importance of membrane-based artificial lung technology has been re-emphasized after the recent breakout of COVID-19 to treat acute lung-failure patients. The world population, particularly in Korea, is aging at an unprecedented rate, which can increase the demand for better artificial organs (AO) in the near future. Membrane technology plays a key role in artificial organ markets. Among them, membrane-based artificial lung (AL) technology has improved significantly in the past 50 years, but the survival rate of lung-failure patients is still very low. Most AL works focus on the clinical application of the AL device, not on the development of the AL membrane itself. This review summarizes the challenges and recent progress of membrane-based AL technology.