• Journal of Mechanical Science and Technology
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• 제17권10호
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• pp.1411-1422
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• 2003

The detection of free spaces between obstacles in a scene is a prerequisite for navigation of a mobile robot. Especially for stereo vision-based navigation, the problem of correspondence between two images is well known to be of crucial importance. This paper describes multi-range approach of area-based stereo matching for grid mapping and visual navigation in uncertain environment. Camera calibration parameters are optimized by evolutionary algorithm for successful stereo matching. To obtain reliable disparity information from both images, stereo images are to be decomposed into three pairs of images with different resolution based on measurement of disparities. The advantage of multi-range approach is that we can get more reliable disparity in each defined range because disparities from high resolution image are used for farther object a while disparities from low resolution images are used for close objects. The reliable disparity map is combined through post-processing for rejecting incorrect disparity information from each disparity map. The real distance from a disparity image is converted into an occupancy grid representation of a mobile robot. We have investigated the possibility of multi-range approach for the detection of obstacles and visual mapping through various experiments.

• 한국전자파학회논문지
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• 제20권1호
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• pp.52-59
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• 2009

현대의 레이더는 큰 클러터 환경에서 동작하기 위해 넓은 동적 영역을 요구한다. ADC(Analog-to-Digital Converter)가 발생시키는 스퓨리어스(spurious) 신호는 넓은 동적 영역을 구현하는데 걸림돌이 되고 있다. 본 논문에서는 ADC의 비선형 특성에 따른 능동 위상 배열 레이더 수신기의 이득을 분석하였다. ADC SFDR(Spurious Free Dynamic Range)은 시스템이 요구하는 동적 영역을 한정하고, 제한된 영역내에서 ADC SNR(Signal-to-Noise Ratio) 손실을 고려하여 ADC 동적 영역을 설정하였다. 그리고 계산된 능동 위상 배열 레이더의 안테나단 출력 잡음 전압과 ADC 입력 잡음 전압을 비교하여 수신기의 이득을 구하였다. 끝으로 응용 예제를 통한 전체적인 내용을 살펴보았다.

• Radiation Oncology Journal
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• 제33권4호
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• pp.310-319
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• 2015

Purpose: Follicular lymphoma (FL) is an indolent non-Hodgkin's lymphoma that is highly sensitive to radiotherapy (RT). However, the effectiveness of RT has not been well established. We reviewed our experiences to assess the role of RT for FL and analyze treatment results. Materials and Methods: Retrospective analysis was done on 29 patients who received first RT between January 2003 and August 2013. Of 23 early stage (stage I, II) patients, 16 received RT alone, four received chemotherapy followed by RT, two received RT postoperatively, and one received salvage RT for relapse after resection. Six advanced-stage (stage III, IV) patients received RT after chemotherapy: two received consolidation RT, three received salvage RT for residual lesions, and one received RT for progressive sites. Median RT dose was 30.6 Gy (range, 21.6 to 48.6 Gy). Median follow-up duration was 62 months (range, 6 to 141 months). Results: All patients showed complete response in the radiation field. Eight outfield relapses were reported. Seven patients received salvage treatment (three chemotherapy, four RT). Four patients showed excellent responses, especially to RT. Estimated 5-year and 10-year relapse-free survivals were 72% and 60%. In the RT-alone group, 5-year relapse-free survival was 74.5%. All advanced-stage patients were disease-free with 100% 5-year overall survival. Disease-specific death was noted in only one patient; four others died of other unrelated causes. No significant toxicity was reported. Conclusion: RT resulted in excellent treatment outcomes for all FL stages when used as a primary treatment modality for early stage or salvage-treatment modality for advanced-stage disease.

• Radiation Oncology Journal
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• 제30권2호
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• pp.62-69
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• 2012

Purpose: To evaluate the treatment outcome and prognostic factor of postoperative radiotherapy for extremity soft tissue sarcoma (STS). Materials and Methods: Forty three patients with extremity STS were treated with conservative surgery and postoperative radiotherapy from January 1981 to December 2010 at Korea University Medical Center. Median total 60 Gy (range, 50 to 74.4 Gy) of radiation was delivered and 7 patients were treated with chemotherapy. Results: The median follow-up period was 70 months (range, 5 to 302 months). Twelve patients (27.9%) sustained relapse of their disease. Local recurrence occurred in 3 patients (7.0%) and distant metastases developed in 10 patients (23.3%). The 5-year overall survival (OS) was 69.2% and disease free survival was 67.9%. The 5-year local relapse-free survival was 90.7% and distant relapse-free survival was 73.3%. On univariate analysis, no significant prognostic factors were associated with development of local recurrence. Histologic grade (p = 0.005) and stage (p = 0.02) influenced the development of distant metastases. Histologic grade was unique significant prognostic factor for the OS on univariate and multivariate analysis. Severe acute treatment-related complications, Common Terminology Criteria for Adverse Events (CTCAE) grade 3 or 4, developed in 6 patients (14.0%) and severe late complications in 2 patients (4.7%). Conclusion: Conservative surgery with postoperative radiotherapy achieved a satisfactory rate of local control with acceptable complication rate in extremity STS. Most failures were distant metastases that correlate with tumor grade and stage. The majority of local recurrences developed within the field. Selective dose escalation of radiotherapy or development of effective systemic treatment might be considered.

• Radiation Oncology Journal
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• 제37권4호
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• pp.279-285
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• 2019

Purpose: This study was conducted to compare the outcome of three-dimensional conformal radiotherapy (3D-CRT) and intensity-modulated radiotherapy (IMRT) for the postoperative treatment of biliary tract cancer. Materials and Methods: From February 2008 to June 2016, 57 patients of biliary tract cancer treated with curative surgery followed by postoperative 3D-CRT (n = 27) or IMRT (n = 30) were retrospectively enrolled. Results: Median follow-up time was 23.6 months (range, 5.2 to 97.6 months) for all patients and 38.4 months (range, 27.0 to 89.2 months) for survivors. Two-year recurrence-free survival is higher in IMRT arm than 3D-CRT arm with a marginal significance (25.9% vs. 47.4%; p = 0.088). Locoregional recurrence-free survival (64.3% vs. 81.7%; p = 0.122) and distant metastasis-free survival (40.3% vs. 55.8%; p = 0.234) at two years did not show any statistical difference between two radiation modalities. In the multivariate analysis, extrahepatic cholangiocarcinoma, poorly-differentiated histologic grade, and higher stage were significant poor prognostic factors for survival. Severe treatment-related toxicity was not significantly different between two arms. Conclusions: IMRT showed comparable results with 3D-CRT in terms of recurrence, and survival, and radiotherapy toxicity for the postoperative treatment of biliary tract cancer.

• Journal of Korean Neurosurgical Society
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• 제30권1호
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• pp.20-25
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• 2001

Objectives : A substantial number of craniopharyngiomas recur despite gross total excision. The purpose of our study was to investigate pattern of recurrence and to verify prognostic factors for recurrence after gross total excision of craniopharyngiomas in children. Methods : A series of 36 patients with craniopharyngiomas were reviewed. All patients had undergone gross total excision and none of them received radiotherapy after initial surgery. Fifteen were girls and twenty-one were boys, with a mean age of 7.3 years(range, one to 15 years). The mean follow-up period was 52 months(range, one to 149 months). Recurrence was noted in 14 patients within 83 months(mean 31.4 months). Results : The overall three-year recurrence free survival rate was 65%, and the five-year recurrence-free survival rate was 55%. Regular neuroimaging follow-up at six to 12-month intervals detected tumor recurrence of a smaller size before symptoms developed(p<0.05). At the first surgical procedure, the optic nerve/chiasm(n=23) was the most common adhesion site. The most frequent sites of recurrence were the optic nerve/chiasm(n=6) and the pitiutary fossa(n=6). Tumor location was the single significant clinical predictor of recurrence. The five-year recurrence-free survival rate was 39% for those who had an intrasellar tumor component and 81% for those who did not (p<0.05). Conclusion : Craniopharyngiomas with intrasellar components should be followed cautiously and regular followup of patients should be emphasized, even when the tumors are totally resected.

• Journal of Microbiology and Biotechnology
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• 제20권1호
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• pp.110-116
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• 2010

Lactic acid (LA) fermentation by Lactobacillus salivarius ATCC 11741 immobilized on loofa sponge (LS) was evaluated. To increase the surface area of LS for cell immobilization, $H_2O_2$ and chitosan were introduced as surface modifying reagents. Four chitosans of different molecular weights were separately coated on LS. All experiments were conducted in shaking flask mode at 100 rpm rotating speed and $37^{\circ}C$ with 5% $CaCO_3$ as a pH regulating agent. The effects of initial glucose concentration were investigated in the range of 20-100 g/l on LA fermentation by free cells. The results indicate that the maximum concentration of LA was produced with 50 g/l glucose concentration. The immobilized cell system produced 1.5 times higher concentration than free cells for 24 h of fermentation. Moreover, immobilized cells can shorten the fermentation time by 2-fold compared with free cells at the same level of LA concentration. At 1% (w/v) chitosan in 2% (v/v) acetic acid, the Yp/s and productivities of various molecular weights of chitosans were insignificantly different. Repeated batch fermentations showed 5 effective recycles with Yp/s and productivity in the range of 0.55-0.85 and 0.90-1.20 g/l.h, respectively. It is evident that immobilization of L. salivarius onto LS permits reuse of the system under these fermentation conditions. Scanning electron micrographs indicated that there were more intact cells on the chitosan-treated LS than on the untreated LS, thus confirming the effectiveness of the LS-chitosan combination when being utilized as a promising immobilization carrier for LA fermentation.

• Journal of Welding and Joining
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• 제20권4호
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• pp.505-509
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• 2002

Pb is considered to be eliminated from solder, due to its toxicity. However, melting temperatures of most Pb-free solders are known higher than that of Sn37Pb. Therefore, there is a difficulty to apply Pb-free solders to electronic industry. Since Sn3Ag8Bi5In has relatively lower melting range as $188~200^{\circ}C$, on this study. Wettability and soldering characteristics of Sn3Ag8Bi5In solder in BGA were investigated to solve for what kind of problem. Zero cross time, wetting time, and equilibrium force of Sn3Ag8Bi5In solder for Cu and plated Cu such as Sn, Ni, and Au/Ni-plated on Cu were estimated. Plated Sn on Cu showed best wettability for zero cross time, wetting time and equilibrium farce. Shear strength of the reflowed joint with Sn3Ag8Bi5In ball in BGA was investigated. Diameter of the ball was 0.5mm, UBM(under bump metallurgy) was $Au(0.5\mu\textrm{m})Ni(5\mu\textrm{m})/Cu(18\mu\textrm{m})$ and flux was RMA type. For the reflow soldering, the peak reflow temperature was changed in the range of $220~250^{\circ}C$, and conveyor speed was 0.6m/min.. The shear strength of Sn3Ag8Bi5In ball showed similar level as those of Sn37Pb. The soldered balls are aged at $110^{\circ}C$ for 36days and their shear strengths were evaluated. The shear strength of Sn3Ag8Bi5In ball was increased from 480gf to 580gf by aging for 5 days.

• Asian Pacific Journal of Cancer Prevention
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• 제15권5호
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• pp.2061-2067
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• 2014

Background: It has been demonstrated that neutrophil:lymphocyte (NLR) and platelet:lymphocyte (PLR) ratios are associated with prognosis in cancer patients. The aim of this study was to investigate whether pretreatment white blood cell (WBC), neutrophil, lymphocyte, monocyte, platelet, basophil and eosinophil counts, LDH level, NLR and PLR are associated with prognosis in patients with malignant pleural mesothelioma (MPM). Materials and Methods: We retrospectively reviewed files of 50 patients who were managed with a diagnosis of MPM between 2005 and 2010. Demographic and clinical characteristics, treatments, response to treatment and prognostic factors were evaluated, along with relationships between pretreatment blood parameters and prognosis. Results: Overall, 38 men and 12 women were included to the study. Mean age was $61.5{\pm}9.4$ years (range: 39-83 years). There was advanced disease in 86% (n=43) and the histological type was epithelial mesothelioma in the majority (82%). Of the cases, 17 (34%) received radiotherapy, while 42 cases underwent first- and second-line chemotherapy, with cisplatin plus pemetrexed as the most commonly used regimen. In the assessment after therapy, it was found that there was complete response in 4 cases (8%), partial response in 10 cases (20%), stable disease in 17 cases (34%) and progression in 19 cases (38%). Median follow-up was 10 months (range: 10 day-30 months). Median overall survival was found to be 20.7 months while median progression-free survival as 10 months. In univariate and multivariate analyses, it was found that factors significantly affecting overall survival included stage (p=0.030), response to treatment (p=0.026) and monocyte count (p=0.004), while factors affecting disease-free survival included NLR (p=0.018), response to treatment (p=0.001), and PLR score (p=0.003). Conclusions: Overall and disease-free survival was found to be better in cases with a WBC count<8.000, platelet count<300,000, and low NLR and PLR scores in malignant pleural mesothelioma.

• 한국광학회지
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• 제18권1호
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• pp.79-83
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• 2007

본 논문에서는 서로 다른 FSR (free spectral range)을 갖는 두 개의 가변 (tunable) 폴리머 링 공진기 기반의 $1{\times}2$ 스위치를 이용하여 광학적 방식의 채널 선택이 가능한 재구성형 (reconfigurable) 마이크로웨이브 (microwave: MW) 필터를 제안하고 구현하였다. 각 링 공진기는 두 개의 링이 연결되어 있으며 한 개의 링 위에 전극이 형성되어 있으며, 이 전극에 전압을 인가함으로써 열광학효과를 통해 On/Off 스위치로서 동작된다. 입력 MW 신호에 의해서 변조된 광신호를 이 스위치를 통해 특정 포트로 라우팅(routing)하고 광검출기를 통해 복원함으로써 두 개의 채널이 선택되는 MW 대역통과 필터 특성을 얻었다. 중심주파수가 10 GHz인 채널 I 이 선택된 경우, 소멸비는 ${\sim}30dB$, 대역폭은 1 GHz, Q값은 10, 최대 소비전력은 4.1 mW였다. 그리고 중심주파수가 20 GHz인 채널II가 선택된 경우에는 소멸비는 ${\sim}30dB$, 대역폭은 2 GHz, Q값은 10, 최대 소비전력은 8 mW였으며, 각 채널 간의 격리도는 24 dB 이상이었다.