• Journal of the Korea Institute of Information and Communication Engineering
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• v.16 no.7
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• pp.1541-1548
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• 2012

This paper proposes a new multipath-based routing protocol on MANETs with Fast-Recovery of failures. The proposed protocol establishes the primary and secondary paths between a source and a destination considering the end-to-end packet reception reliability of routes. The primary path is used to transmit messages, and the secondary path is used to recover the path when detecting failures on the primary path. If a node detects a link failure during message transmission, it can recover the path locally by switching from the primary to the secondary path. By allowing the intermediate nodes to recover locally the route failure, the proposed protocol can reduce the number of packet loss and the amount of control packets for setting up new paths. The simulation result using QualNet simulator shows that the proposed protocol was about 10-20% higher than other protocols in terms of end-to-end message delivery ratio and the fault recovery time in case of link fault was about 3 times faster than the other protocols.

• Journal of Broadcast Engineering
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• v.18 no.2
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• pp.185-195
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• 2013

In this paper, we propose a video summarization technique on a smartphone, based on spatiotemporal saliency. The proposed technique detects scene changes by computing the difference of the color histogram, which is robust to camera and object motion. Then the similarity between adjacent frames, face region, and frame saliency are computed to analyze the spatiotemporal saliency in a video clip. Over-segmented hierarchical tree is created using scene changes and is updated iteratively using mergence and maintenance energies computed during the analysis procedure. In the updated hierarchical tree, segmented frames are extracted by applying a greedy algorithm on the node with high saliency when it satisfies the reduction ratio and the minimum interval requested by the user. Experimental result shows that the proposed method summaries a 2 minute-length video in about 10 seconds on a commercial smartphone. The summarization quality is superior to the commercial video editing software, Muvee.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.3
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• pp.1711-1717
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• 2014

There have been many studies on IEEE 802.15.4 for home area networks(HAN) in Smart Grids. Existing unslotted or slotted IEEE 802.15.4 has almost not met strict conditions of the U.S. Department Of Energy(DOE). This study proposed a improved algorithm that reduces collisions, delay time and changes in the delay time. For this purpose, numbers were given to nodes to make the transmission in the order of the node numbers. Since the probability of the occurrence of collisions would decrease compared to random transmission if the nodes were given numbers, Backoff time was set at 0. In the proposed Numbered-Unslotted-ZeroBackoff algorithm, when the packet size was 133 octets and less than 180 packets per second occurred, it was found that packet delivery ratio was over 99.99%, and that all the maximum delay, the mean delay and the minimum delay were less than 0.02 seconds. This paper could confirm that the algorithm proposed in this study met the strict conditions of the DOE.

• The KIPS Transactions:PartC
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• v.9C no.4
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• pp.581-588
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• 2002

In this paper, we newly propose the optical CDMA routing scheme for the radio access network. At the radio base station (RBS), the received radio signals are multiplied by the PN codes and converted to the CDMA radio signals. In the next optical CDMAS are performed and multiplxed by using the PN codes which are the addresses of the routing mobile switching center (MSC). At the MSC, the CDMA radio signals are routined to another MSC by the CDM receiver at the routing node. In the case MSC is equal to the desired MSC, the radio signal is correlated by the two-layerd spectrum despreading at a time. Finally we theoretically analyze the signal-to-interference and noise power ratio of regenerated signal and the routing error probability and show the availability of proposed scheme.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38A no.8
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• pp.688-696
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• 2013

In wireless sensor networks, real-time applications have to ensure the timely delivery of real-time data. Recently, OMLRP (On-demand Multi-hop Look-ahead Routing Protocol) has been proposed to improve the timeliness of wireless sensor networks. The protocol needs initialization time to establish multi-hop information based routing path because it performs incremental look-ahead of the information. Consequently, the protocol deteriorates DDSR (Deadline Delivery Success Ratio) as an event moves because it takes little consideration of event mobility. In this paper, we proposed a Real-time Routing for Events Mobility (RREM) which exploits a data redirection in order to improve the DDSR of moving events. Instead of recollecting muti-hop look-ahead information, the RREM redirects the data to a sensor node holding the information collected in a previous round. We verify the timeliness and energy efficiency of RREM using various MatLab simulations.

• Journal of KIISE
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• v.44 no.7
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• pp.710-718
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• 2017

As graphs are becoming increasingly large, the costs for storing and managing data are increasing continuously. Shortest path discovery over a large graph requires long running time due to frequent disk I/Os and high complexity of the graph data. Recently, graph summarization techniques have been studied, which reduce the size of graph data and disk I/Os by representing highly dense subgraphs as a single super-node. Decompressing should be minimized for efficient shortest path discovery over the summarized graph. In this paper, we analyze the decompression performance of a summarized graph and propose an approximate technique that discovers the shortest path quickly with a minimum error ratio. We also propose an exact technique that efficiently discovered the shortest path by exploiting an index built on paths containing super-nodes. In our experiments, we showed that the proposed technique based on the summarized graph can reduce the running time by up to 70% compared with the existing techniques performed on the original graph.

• Clinical and Experimental Pediatrics
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• v.59 no.10
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• pp.408-413
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• 2016

Purpose: This study investigated predictors of unresponsiveness to second-line intravenous immunoglobulin (IVIG) treatment for Kawasaki disease (KD). Methods: This was a single-center analysis of the medical records of 588 patients with KD who had been admitted to Asan Medical Center between 2006 and 2014. Related clinical and laboratory data were analyzed by univariate and multivariate logistic regression analyses. Results: Eighty (13.6%) of the 588 patients with KD were unresponsive to the initial IVIG treatment and received a second dose. For these 80 patients, univariate analysis of the laboratory results obtained before administering the second-line IVIG treatment showed that white blood cell count, neutrophil percent, hemoglobin level, platelet count, serum protein level, albumin level, potassium level, and C-reactive protein level were significant predictors. The addition of methyl prednisolone to the second-line regimen was not associated with treatment response (odds ratio [OR], 0.871; 95% confidence interval [CI], 0.216-3.512; P=0.846). Multivariate analysis revealed serum protein level to be the only predictor of unresponsiveness to the second-line treatment (OR, 0.160; 95% CI, 0.028-0.911; P=0.039). Receiver operating characteristic curve analysis to determine predictors of unresponsiveness to the second dose of IVIG showed a sensitivity of 100% and specificity of 72% at a serum protein cutoff level of <7.15 g/dL. Conclusion: The serum protein level of the patient prior to the second dose of IVIG is a significant predictor of unresponsiveness. The addition of methyl prednisolone to the second-line regimen produces no treatment benefit.

• Radiation Oncology Journal
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• v.31 no.3
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• pp.131-137
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• 2013

Purpose: We evaluated treatment outcomes of thymic carcinomas to determine prognostic factors for survival. Materials and Methods: Between May 1988 and May 2009, 41 patients had pathologic diagnosis of thymic carcinoma in Seoul National University Hospital, Seoul, Korea. Of these, 40 patients were followed up to 188 months after treatment. The mean age of all patients was 58.3 years and male to female ratio was 23 to 17. Results: Among 30 patients who underwent surgical resection, 26 achieved R0 resection and postoperative radiotherapy (PORT) was performed in 22 patients (73%). Various chemotherapeutic regimens were given with local treatment modalities, surgery and/or radiotherapy, in 12 patients. The 5-year locoregional control (LRC), distant metastasis-free survival, progression-free survival (PFS), and overall survival were 79.4%, 53.0%, 42.6%, and 63.6%, respectively. Patients with Masaoka stage I or II showed excellent prognosis of 5-year PFS around 90%. In advanced stages, invasion of the great vessels or atrium by thymic carcinomas was negative prognostic factor for PFS in univariate analysis. Lymph node involvement was statistically significant factor for LRC and PFS. Local or regional recurrence was infrequent after surgical resection followed by PORT, while distant metastasis was the major component of treatment failure. Conclusion: Complete resection followed by PORT provided remarkable local control without severe acute toxicities in patients with stage II and favorable stage III thymic carcinoma. Invasion of the great vessels or atrium was statistically significant prognostic factor for PFS.

• Journal of Chest Surgery
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• v.24 no.1
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• pp.72-82
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• 1991

From May 1978 to Sep. 1990, 106 patients who had been diagnosed as primary lung cancer and operated on at the Department of Thoracic & Cardiovascular Surgery, Han Yang University, were clinically evaluated. 1. The peak incidence of age was 5th decade of life[37.7%] and 6th decade[29.2%]. Male to female ratio was 3.8: l. 2. Most of symptoms were respiratory, which were cough, chest pain, hemoptysis, and asymptomatic cases were 2.9%. 3. Histopathologic classifications were squamous cell carcinoma[53.7%], adenocarcinoma [23.8%], bronchioloalveolar cell carcinoma[6.6%], undifferentiated large cell carcinoma[6.6%], small cell carcinoma[3.8%], adenosquamous carcinoma[3.8%] and others[1.8%]. 4. Methods of operation were pneumonectomy 49.1%[52cases], lobectomy 21%[22cases] bilobectomy[6cases], lobectomy with wedge resection[3cases], exploration 21.9%[23cases], and resectability was 78.3%. 5. Staging classifications were Stage I [22.6%], Stage II [11.3%], Stage IIIa[42.6%], Stage IIIb[21.7%] and Stage lV[1.6%]. Resectability by Stage; Stage I was 100%, II 100%, IIIa 84.4% and IIIb 30.4%. 6. Causes of most of inoperable cases were invasion of mediastinal structures and diffuse chest wall, and others were contralateral lymph node invasion and malignant pleural effusion. 7. Operative mortality was 6.7% which caused by arrhythmia, sepsis, pulmonary edema, and radiation pneumonitis. 8. On the long term follow up of the resectable cases, overall 1 year survival rate was 58.5 %, 2 year 39%, and 5 year 19.5%. Five year survival rate was 40% in Stage I, 25% in Stage II and 11.7% in Stage Illa. As for the method of operation, the higher 5 year survival rate was observed in lobectomies[33.3%] than in pneumonectomies[10.3%].

• Journal of Chest Surgery
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• v.22 no.6
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• pp.1013-1024
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• 1989

One hundred and seventy two patients of primary lung cancer, confirmed by tissue diagnosis at the Dept. of Thoracic and Cardiovascular Surgery in Korea University Hospital between June 1973 and August 1988, were evaluated and restaged with New International TNM classification, and the actuarial survival rate was obtained using Kaplan-Meier equation. The results of analysis were as follows. 1. Male to female ratio was 3.8:1, and prevalent age groups were sixth and seventh decades [76.4 %]. 2. The most common subjective symptom was cough [55.2 %], and 67.4 % of all patients were visited to hospital less than 6 months of symptoms. 3. Positive rates for tissue diagnosis were 100% in open chest or metastatic lymph node biopsy, 80 % in mediastinoscopic biopsy, 60 % in pleural biopsy, 59 % in pleural fluid cytology, 36% in bronchoscopic biopsy, and 22 % in sputum cytology. 4. The order of frequency of cell type was squamous cell carcinoma [53.0%], adenocarcinoma [22.0 %], small cell carcinoma [14.5 %], and so on. 5. Operability and resectability were 44% and 62% respectively, but they were improved recently. 6. Open and closure was done in 44 % of operated patients, uni or bilobectomy in 38 % and pneumonectomy in 24 %. 7. Overall operative mortality rate was 2.6 %. 8. The order of frequency of stage level was S3b [42.0 %], S3a [25.1 %], S1 [15.6%], and so on. 9. Distant metastasis, i.e. stage 4, was noted in 9.5 % of cases, and the sites of frequency were bone, brain, skin, and so on. 10. Actuarial survival rate was 1 year 48.2%, 2 year 36.9%, 3 year 31.2%, and 5 year 20.8%. According to above listed factors, 5 year survival rate was highest in squamous cell carcinoma, lobectomized cases, stage 1, NO in TNM system, and resectable cases. But T factor in TNM system and radiation therapy in nonresectable cases did not show statistical significance in life expectancy.