• KSII Transactions on Internet and Information Systems (TIIS)
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• v.15 no.12
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• pp.4600-4616
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• 2021

In cognitive radio networks where unlicensed secondary users opportunistically access to licensed spectrum unused by licensed primary users, spectrum sensing is one of the key issues in order to effectively use the frequency resource. For enhancing the sensing performance in energy detection-based spectrum sensing, spatial diversity based on multiple antennas is utilized. However, the sensing performance can be degraded when antennas are spatially correlated, resulting in inducing the harmful interference to primary users. To overcome this problem, in this paper, an advanced energy detector is proposed. In the proposed sensing method, a weight matrix based on the eigenvalues of the spatial channels without any prior information on the primary signals is defined and utilized. In numerical simulations, it is shown that the proposed detector outperforms the conventional detector with regard to false-alarm and detection probabilities when antenna are spatially correlated.

• Phonetics and Speech Sciences
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• v.15 no.4
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• pp.11-16
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• 2023

The present study examines how a cognitive attention affects Korean learners of English (L2) in perceiving the English stop voicing distinction (/d/-/t/). This study tested the effect of attentional distractor on primary and non-primary acoustic cues, focusing on the role of Voice Onset Time (VOT) and fundamental frequency (F0). Using the dual-task paradigm, 28 Korean adult learners of English participated in the stop identification task carried with (distractor) and without (no-distractor) arithmetic calculation. Results showed that when distracted, Korean learners' sensitivity to VOT decreased as priorly reported with native English speakers. Furthermore, as F0 is a primary cue for a L1 Korean stop laryngeal contrast, its role in L2 English voicing distinction was also affected by a distractor, without compensating for the reduced VOT sensitivity. These findings suggest that flexible use of multiple cues in L1 is not necessarily beneficial for L2 phonological processing when coping with a adverse listening condition.

• Journal of Chest Surgery
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• v.35 no.10
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• pp.764-767
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• 2002

An unusual case of primary leiomyosarcoma at the left lower posterior chest wall with metastasis to the right lung parenchyme is presented. The patient was a 43-year-old man who was asymptomatic but a slow growing hard mass was noted at the left lower posterior chest wall. The chest computed tomography showed a tumor at the left lower posterior chest wall with multiple metastasis to the right lung. The left lower posterior chest wall mass was examined by percutaneous needle aspiration and it was revealed as rhabdomyosarcoma histologically. En bloc resection to the left lower posterior chest wall tumor and metastasectomy to the multiple nodules in the right lung were done and pathological examination finally revealed primary leiomyosarcoma at the left lower posterior chest wall with multiple metastasis to the right lung. Chemotherapy was scheduled as adjunctive measure.

• Journal of Environmental Science International
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• v.22 no.8
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• pp.953-963
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• 2013

Reliable long-term streamflow forecasting is invaluable for water resource planning and management which allocates water supply according to the demand of water users. Forecasting of seasonal inflow to Andong dam is performed and assessed using statistical methods based on hydrometeorological data. Predictors which is used to forecast seasonal inflow to Andong dam are selected from southern oscillation index, sea surface temperature, and 500 hPa geopotential height data in northern hemisphere. Predictors are selected by the following procedure. Primary predictors sets are obtained, and then final predictors are determined from the sets. The primary predictor sets for each season are identified using cross correlation and mutual information. The final predictors are identified using partial cross correlation and partial mutual information. In each season, there are three selected predictors. The values are determined using bootstrapping technique considering a specific significance level for predictor selection. Seasonal inflow forecasting is performed by multiple linear regression analysis using the selected predictors for each season, and the results of forecast using cross validation are assessed. Multiple linear regression analysis is performed using SAS. The results of multiple linear regression analysis are assessed by mean squared error and mean absolute error. And contingency table is established and assessed by Heidke skill score. The assessment reveals that the forecasts by multiple linear regression analysis are better than the reference forecasts.

• Nuclear Engineering and Technology
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• v.35 no.3
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• pp.179-190
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• 2003

The multiple steam generator tube rupture (SGTR) event scenario with available safety systems was experimentally and analytically evaluated. The experiment was conducted on the large scaled test facility to simulate the multiple SGTR event and investigate the effectiveness of operator actions. As a result, it indicated that the opening of pressurizer power operated relief valve was significantly effective in quickly terminating the primary-to-secondary break flow even for the 6.5 tubes rupture. In the analysis, the recent version of RELAP5 code was assessed with the test data. It indicated that the calculations agreed well with the measured data and that the plant responses such as the water level and relief valve cycling in the damaged steam generator were reasonably predicted. Finally, sensitivity study on the number of ruptured tubes up to 10 tubes was performed to investigate the coolant release into atmosphere. It indicated that the integrated steam mass released was not significantly varied with the number of ruptured tubes although the damaged steam generator was overfilled for more than 3 tubes rupture. These findings are expected to provide useful information in understanding and evaluating the plant ability to mitigate the consequence of multiple SGTR event.

• Journal of Korean Neurosurgical Society
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• v.48 no.3
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• pp.263-267
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• 2010

Although cerebellar hemangioblastomas are histopathologically benign, they yield a degree of malignant clinical behavior in long-term follow-up. We present two cases of long-term progression of renal cell carcinoma, which had been diagnosed as renal cysts during treatment for cerebellar hemangioblastoma. A 14-year-old male with von Hippel-Lindau disease was admitted for a cerebellar hemangioblastoma with multiple spinal hemangioblastomas and a renal cyst. After primary total resection of the cerebellar hemangioblastoma, the patient required two further surgeries after 111 and 209 months for a recurrent cerebellar hemangioblastoma. Furthermore, he underwent radical nephrectomy as his renal cyst had progressed to renal cell carcinoma 209 months after initial diagnosis. A 26-year-old male presented with multiple cerebellar hemangioblastomas associated with von Hippel-Lindau disease and accompanied by multiple spinal hemangioblastomas and multiple cystic lesions in the liver, kidney, and pancreas. He underwent primary resect'lon of the cerebellar hemangioblastoma in association with craniospinal radiation for multiple intracranial/spinal masses. Unexpectedly, a malignant glioma developed 83 months after discovery of the cerebellar hemangioblastoma. At the same time, renal cell carcinoma, which had developed from an initial renal cyst, was diagnosed, and a radical nephrectomy was performed. In the view of long term clinical course, cerebellar hemangioblastoma associated with von Hipple-Lindau disease may redevelop even after primary total resection. In addition, associated lesions such as renal cysts may also progress to malignancy after the passing of a sufficient length of time.

• Journal of Korean Institute of Industrial Engineers
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• v.10 no.2
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• pp.17-27
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• 1984

This paper is concerned with a branched pipe network system which transports some fluids or gas from multiple sources to multiple demand nodes. A nonlinear programming model is proposed for determining junction locations simultaneously with selection of pipe sizes and pump capacities such that the capital and operating costs of the system are minimized over a given planning horizon. To solve the model, a hierarchical decomposition method is developed with the junction location being the primary variable. With some values fixed for the primary, the other decision variables are found by linear programming. Then, using the postoptimality analysis of LP, junction locations are adjusted. We repeat this process until an optimum is approached. A simple example of designing a water distribution network is solved to illustrate the optimization procedure developed.

• Journal of Yeungnam Medical Science
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• v.5 no.2
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• pp.221-230
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• 1988

Though the occurrence of multiple primary malignant tumor is a rare finding but the reported cases of it has increased in recent years. We collected multiple primary cancer of different organ, tissue and the multicentric origin of bilaterally paired organs. This paper reports 6 cases of multiple primary malignant tumors which were experienced at Yeungnam university hospital in Taegu during the past 2 years with review of journals. The results were as follows. 1. The incidence of multiple primary cancer was 0.31% for 2 years(1987-1988). 2. The ratio between male and female was 1:1 and mean age of incidence was 54.1 years. 3. The ratio between synchronous and metachronous(interval more than 6 months) was 1:1. 4. The time interval between first and second cancer was average 2.7 years in metachronous cases. 5. The most frequent involved organ was stomach, breast and colon in order of frequency. 6. The incidence of familial cancer associations was found in one out of 6 cases. 7. The test of DNCB, multi test CMI and ratio of T4 to T8 were performed in 4 cases but there was no definitive evidence of abnormality. We concluded that every effort should be made to discover the presence of synchronous malignancies in the patients who are being treated for a known tumor, and also special care should be given to detect new metachronous lesions is required.

• Tuberculosis and Respiratory Diseases
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• v.47 no.3
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• pp.331-338
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• 1999

Background: Nearly 10% of cancer patients will develop a second primary cancer within ten years after surgical removal of the primary tumor. The detection of risk factors for developing multiple primary tumors would be important This study was conducted to evaluate the clinical characteristics and abnormal p53 expression of lung cancer associated with multiple primary cancer(MPC). Method: Clinical characteristics and abnormal p53 expression were compared between 20 cases of lung cancer(NSCLC ; 16 cases, SCLC ; 4 cases) associated with MPC and 26 cases of primary non-small cell lung cancer. Result: MPC associated with lung cancer was gastric cancer(8), lung cancer(2), esophageal cancer(2), colon cancer(2), laryngeal cancer(1), bladder cancer(1), small bowel cancer(l), adrenal cancer(1), hepatocellular carcinoma(1), and breast cancer (1) in order. The clinical stage of primary NSCLC was relatively advanced, but NSCLC associated with MPC was even distribution at each stage. The detected incidences of abnormal p53 expressions were 62.5% in NSCLC associated with MPC and 76.9% in primary NSCLC(p>0.05). Conclusion: There was no difference in abnormal p53 expression between non-small cell carcinoma associated with multiple primary cancer and primary non-small cell carcinoma.

• IEIE Transactions on Smart Processing and Computing
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• v.3 no.4
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• pp.181-190
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• 2014

This paper reports a cognitive radio network architecture based on overloaded multicarrier direct sequence code division multiple access (O-MC-DS-CDMA). The O-MC-DSCDMA technique combines CDMA with a multicarrier modulation technique to overcome the channel fading effects. In this technique, secondary users are enabled to share the available bandwidth with the existing primary users. Two sets of orthogonal Gold codes are used to support the primary and secondary users simultaneously. The orthogonality between the spreading codes is lost due to the non-zero cross correlation between the codes and the timing synchronization error in the uplink transmission, which causes interference between primary and secondary users. This paper proposes two modified hybrid parallel/successive interference cancellation techniques for primary and secondary user base station receivers with multiple antennas to suppress the interference among users. Interference among the same group of users is cancelled by parallel interference cancellation and the interference among groups is cancelled using successive interference cancellation. The simulation results confirmed that the proposed modified interference cancellation techniques show better BER performance over conventional interference cancellation techniques.