• Journal of Yeungnam Medical Science
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• v.13 no.2
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• pp.225-233
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• 1996

From August 1992 to July 1996, 63 consecutive patients underwent coronary artery bypass surgery. The mean age of these patient was 57 years(range form 30 to 71years). There were 44 men and 19 women. Preoperative 12 patients had stable angina pectoris and 23 patients were unstable angina pectoris. 8 patients had previous myocardial infarctation history and emergency or urgent myocardial revascularization were performed in 9 cases. In the risk factors of coronary atherosclerosis, 25 patients(40%) were hypercholesterolemia, 38 patients(60%) have smoking history and 19 patients(30%) have hypertension history. In the patterns of disease, 9 patients were single vessel disease, 18 patients were two vessele disease and 33 patients were three vessel disease. We performed total 284 distal anastomosis(mean 3.5 anastomosis per patient) and performed one case of ascending aorta graft interposition, two cases of mitral valve replacement, one case of aortic valve replacement, one case of ventricular septal defect repair and one case of atrial septal defect repair and the mean aortic cross clamp time was 115.3 minutes. The common complications were arrhythmia(7cases), wound infection(5cases), perioperative myocardial infarction(4cases), reoperation for bleeding control(4cases) and stroke(4cases). There were six hospital deaths due to low cardiac output syndrome, ventricular arrhythmia and respiratory failure. In the evaluation of operative risk factors, preoperative intravenous nitroglycerin requirement and prolonged aortic cross clamp tirne(>2hours) were found to be predective factor of morbidity and old age(>65years) was found to be predective factor of mortality.

• Radiation Oncology Journal
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• v.31 no.4
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• pp.222-227
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• 2013

Purpose: This study was performed to evaluate prognostic factors for survival from first relapse (SFFR) in stage I-III breast cancer patients. Materials and Methods: From June 1994 to June 2008, 3,835 patients were treated with surgery plus postoperative radiotherapy and adjuvant chemotherapy for stage I-III breast cancer at Samsung Medical Center. Among them, a total of 224 patients died by June 2009, and 175 deaths were of breast cancer. Retrospective review was performed on medical records of 165 patients who met the inclusion criteria of this study. Univariate and multivariate analysis were done on survivals according to variables, such as age, stage, hormone status of tumor, disease-free interval (DFI), sites of first failure, number of organs involved by recurrent disease (NOR), application of salvage treatments, and existence of brain or liver metastasis (visceral metastasis). Results: Patients' median overall survival time was 38 months (range, 8 to 123 months). Median SFFR was 17 months (range, 5 to 87 months). Ninety percent of deaths occurred within 40 months after first recurrence. The patients with SFFR ${\leq}1$ year had tendency of triple-negativity, shorter DFI (${\leq}2$ years), larger NOR (>3), visceral metastasis for first relapse than the patients with SFFR >1 year. In multivariate analysis, longer DFI (>2 vs. ${\leq}2$ years), absence of visceral metastasis, and application of salvage treatments were statistically significant prognosticators for longer SFFR. Conclusion: The DFI, application of salvage treatments, and visceral metastasis were significant prognostic factors for SFFR in breast cancer patients.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.43 no.10 s.352
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• pp.79-89
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• 2006

TCP is the most widely used transport protocol in Internet applications that guarantees a reliable data transfer. But, in the wireless multi-hop networks, TCP performance is degraded because it is designed for wired networks. The main reasons of TCP performance degradation are contention for wireless medium at the MAC layer, hidden terminal problem, exposed terminal problem, packet losses in the link layer, unfairness problem, reordering problem caused by path disconnection, bandwidth waste caused by exponential backoff of retransmission timer due to node's mobility and so on. Specially, in the mobile ad-hoc networks, discrepancy between a station's transmission range and interference range produces hidden terminal problem that decreases TCP performance greatly by limiting simultaneous transmission at a time. In this paper, we propose a new MAC algorithm for mobile ad-hoc networks to solve the problem that a node can not transmit and just increase CW by hidden terminal. In the IEEE 802.11 MAC DCF, a node increases CW exponentially when it fails to transmit, but the proposed algorithm, changes CW adaptively according to the reason of failure so we get a TCP performance enhancement. We show by ns-2 simulation that the proposed algorithm enhances the TCP performance by fairly distributing the transmission opportunity to the failed nodes by hidden terminal problems.

• The Journal of Small Business Innovation
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• v.19 no.3
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• pp.1-16
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• 2016

Korean government had used public 'credit guarantee schemes' (CGS) as a counter-cyclical measure. However, it is still controversial about the effectiveness of policy financing on the SMEs. Criticism on policy financing involves the argument that supporting enterprises hampers competition and innovation of SMEs by increasing their dependence on the government and delays the exit of marginal firms. In this paper, we investigate how to effectively build up the rationale of running public CGSs. At the same time, we propose the ways to coexist of public credit guarantee and market-based private finance system for SMEs. First, CGS, as a counter-cyclical function, must coexist with the private financial system by compensating the market failure caused by pro-cyclical behavior of the private financial market. Second, CGS has the comparative advantages, compared to both the interest rate policy of the central bank and fiscal policy of the government. The credit guarantee is the symptomatic treatment that could revitalize the economy shortly by providing liquidity. Also, knowing that CGS is provided based on the leverage ratio defined by outstanding guarantee divided by capital fund, public 'credit guarantee' (CG) has an advantage that is free from the risk of government deficit. Third, the reason for existence of the CGS should be founded in supporting services for SMEs, available only in a public sector that is difficult to expect from private banks. In this regard, it is desirable to strengthen the publicness of credit guarantee over the support for start-ups, growing companies, the improvement of productivity, increase of exports, a long-term investment in facilities, the employment-creating businesses, and innovative enterprises.

• Asian Pacific Journal of Cancer Prevention
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• v.16 no.15
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• pp.6673-6679
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• 2015

Background: Male breast cancer is a rare neoplasm, and its treatments are based on those of female breast cancer. This study aimed to analyze 20 years of male breast cancer clinical characteristics and treatment results from the Middle Black Sea Region of Turkey. Materials and Methods: A retrospective analysis of 16 male breast cancer patients treated in our tertiary hospital between 1994 and 2014 was performed. Epidemiologic data, tumor characteristics, and treatments were recorded and compared with 466 female breast cancer ((premenopausal; n = 230) + (postmenopausal n = 236)) patients. The 5-year disease-free and overall survival rates were calculated. Results: Male breast cancer constituted 0.1% of all malignant neoplasms in both sexes, 0.2% of all malignant neoplasms in males, and 0.7% of all breast cancers. The mean patient age in this study was $59.8{\pm}9.5$ (39-74) years. The mean time between first symptom and diagnosis was $32.4{\pm}5.3$ (3-60) months. Histology revealed infiltrative ductal carcinoma in 81.3% of patients. The most common detected molecular subtype was luminal A, in 12 (75%) patients. Estrogen receptor rate (93.8%) in male breast cancer patients was significantly higher than that in female breast cancer (70.8% in all females, p = 0.003; 68.2% in postmenopausal females, p = 0.002) patients. Most of the tumors (56.3%) were grade 2. Tumor stage was T4 in 50% of males. The majority (56.3%) of the patients were stage III at diagnosis. Surgery, chemotherapy, radiotherapy and endocrine-therapy were applied to 62.5%, 62.5%, 81.2% and 73.3%, respectively. Loco-regional failure did not occur in any of the cases. All recurrences were metastastic. The 5-year disease-free and overall survival rates in male breast cancer patients were 58% and 68%, respectively. Conclusions: Tumors found in male breast cancer patients were similar in size to tumors found in females, but they advanced to T4 stage more rapidly because of the lack of breast parenchymal tissues. The rate of estrogen receptor expression tended to be higher in male breast cancer patients than in female breast cancer patients. Metastasis is the most important problem in initially non-metastatic male breast cancer patients.

• Clinics in Shoulder and Elbow
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• v.15 no.1
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• pp.32-36
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• 2012

Purpose: The purpose of this study was to evaluate the radiologic and clinical outcomes after intercalary tricortical iliac bone graft with plate fixation for the nonunion of midshaft clavicular fractures. Material and Methods: Between September 2007 and May 2011, 10 patients who were treated by the intercalary tricortical iliac bone graft, with plate fixation for clavicle nonunion, were studied. The mean follow-up period was 30.7 (12~57) months. After the sclerotic bone was excised to the bleeding cortical bone, we interposed the tricortical iliac bone to provide structural support and restore clavicle length, and then fixed the plate and screws. The radiologic outcomes on the serial plain radiographs and clinical outcomes, according to UCLA, ASES and Quick DASH scores, were analyzed. Results: Bony union was obtained in all cases (100%) and the average union time was 18.4 (14~24) weeks. The average respective UCLA and ASES scores improved from 16.7 and 52.1 preoperatively to 27.4 and 83.6 postoperatively (p<0.05). The average Quick DASH score was 40.5, at the final follow-up. Complications were 2 shoulder stiffness, and one case had removal of device and arthroscopic surgery at 11 months, postoperatively. There were no implant failure or infection. Conclusion: Intercalary tricortical iliac bone graft, with plate fixation for the nonunion of midshaft clavicular fractures, is a good option that can provide structural support and restore clavicle length, as well as high union rate.

• Journal of the Korea Concrete Institute
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• v.18 no.4 s.94
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• pp.527-534
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• 2006

This paper outlines a new strengthening technique for concrete beams using externally unbended high-strength bars. The advantages of proposed method lie in speed and simplicity of construction compared to the alternative strengthening method. Externally unbended reinforcement retains many of the advantages over external unbended prestressed tendons. It eliminates time consuming stressing operations. Clearance requirements around anchorages are reduced as access is not required for prestressing jacks. Test results of eight specimens on reinforced concrete beams using different reinforcement materials such as carbon fiber sheet, steel plate and high-tension bar are reported. The beam strengthened by carbon fiber sheet showed a brittle failure mode due to the separation of fiber. As a result of draped profile of external bar, the maximum strength of the beam were increased by up to 212 percent and the deflections were reduced by up to 65 percent. Test results show that the beams reinforced with high-tension bar are superior to reference specimens, especially for the strength and deformation capacity.

• Fire Science and Engineering
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• v.32 no.4
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• pp.25-34
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• 2018

This study investigated the development of a fire alarm system with evacuation lighting and voice alarm functions. The performance of a fire detector and system with independently built-in evacuation lighting and voice alarm functions was confirmed for early recognition of fire and to allow visibility of the evacuation route in the event of fire. This new system satisfied model recognition and product testing technological standards with 1.62 lx average illumination, 89.7 dB average sound and 86.1 dB average voice. From additionally testing the evacuation performance of this new system, it was confirmed that the evacuation time decreased by 63.08% to 67.82% under the experimental conditions compared to conventional systems. The new system can minimize fire damage by setting off voice alarms to prevent failure of fire recognition and by flashing emergency lighting to secure the minimum required visibility range for evacuation. Therefore, it is considered that it will be utilized as a fire alarm system with appropriateness and usefulness by considering people with hearing or visual impairment.

• Korean Journal of Materials Research
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• v.9 no.9
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• pp.919-925
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• 1999

Grain boundary characteristics and corrosion behavior of Alloy 600 material were investigated using the concept of grain boundary control by thermomechanical treatment(TMT). The grain boundary character distribution (GBCD) was analyzed by electron backscattered diffraction pattern. The effects of GBeD variation on intergranular at tack(JGA) and primary water stress corrosion cracking(PWSeC) were also evaluated. Changes in the fraction of coinci dence site lattice(CSL) boundaries in each cycle of TMT process were not distinguishable, but the total eSL boundary frequencies for TMT specimens increased about 10% compared with those of the commercial Alloy 600 material. It was found from IGA tests that the resistance to IGA was improved by TMT process. However, it was found from PWSCC test that repeating of TMT cycles resulted in the gradual decrease of the time to failure and the maximum load due to change in grain boundary characteristics, while the average crack propagation rate of primary crack increased mainly due to suppression of secondary crack propagation. It is considered that these corrosion characteristics in TMT specimens is attributed to 'fine tuning of grain boundary' mechanism.

• Journal of the korean academy of Pediatric Dentistry
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• v.34 no.1
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• pp.162-168
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• 2007

Impaction of the maxillary central incisor may cause social, esthetic, and functional problems in children. There are various means of treatment for the inverted maxillary central incisor, such as extraction, surgical opening followed by orthodontic traction surgical repositioning or intra-alveolar autotransplantation prior to extraction. In this case, we surgically repositioned the inverted maxillary central incisor to normal semi-erupted position in a 5-year-old boy The developmental stage of the inverted tooth was Nolla's 6.5, which indicates formation of less than one third of the root. After surgical reposition, we did follow-up for 21 months, expecting spontaneous growth Unfortunately, poor prognosis was noted further root was not observed. Such failure seems to originate from possible injury on Hertwig's epithelial root sheath by surgical trauma. We performed surgical repositioning to retain the tooth instead of extraction. However, arrest of root development occurred which is one of the critical complications. In order to increase the success rate of the surgical reposition procedure, minimal surgical trauma is required as well as selection of adequate indication and decision of proper time of treatment considering the stage of root development.