• Asian Pacific Journal of Cancer Prevention
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• v.15 no.2
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• pp.691-694
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• 2014

Background: Tumor length in patients with esophageal cancer (EC) has recently received great attention. However, its prognostic role for EC is controversial. The purpose of our study was to characterize the prognostic value of tumor length in EC patients and offer the optimum cut-off point of tumor length by reliable statistical methods. Materials and Methods: A retrospective analysis was conducted on 71 consecutive patients with EC who underwent surgery. ROC curve analysis was used to determine the optimal cut-off point for tumor length, measured with a handheld ruler after formalin fixation. Correlations between tumor length and other factors were surveyed, and overall survival (OS) rates were compared between the two groups. Potential prognostic factors were evaluated by univariate Kaplan-Meier survival analysis. A P value less than 0.05 was considered significant. Results: There were a total of 71 patients, with a male/female divide of 43/28 and a median age of 59. Characteristics were as follows: squamous/adenocarcinoma, 65/6; median tumor length, 4 (0.9-10); cut-off point for tumor length, 4cm. Univariate analysis prognostic factors were tumor length and modality of therapy. One, three and five year OS rates were 84, 43 and 43% for tumors with ${\leq}4cm$ length, whereas the rates were 75, 9 and 0% for tumors >4 cm. There was a significant association between tumor length and age, sex, weight loss, tumor site, histology, T and N scores, differentiation, stage, modality of therapy and longitudinal margin involvement. Conclusions: Future studies for modification of the EC staging system might consider tumor length too as it is an important prognostic factor. Further assessment with larger prospective datasets and practical methods (such as endoscopy) is needed to establish an optimal cut-off point for tumor length.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.16 no.10
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• pp.2293-2302
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• 2012

New optical transmission links technique for compensating of the distorted wavelength division multiplexed (WDM) signals due to group velocity dispersion (GVD) and self phase modulation (SPM) in single mode fiber (SMF) are proposed. The proposed optical links have optical phase conjugator (OPC) placed at nearby WDM transmitter or receiver and repeater spans with artificial distribution of SMF length and residual dispersion per span (RDPS). It is confirmed that optimal link configuration expanding effective launching power range and effective net residual dispersion (NRD) by improving system performance is that having OPC closely placed at WDM receiver and the gradually descended distribution of SMF length and RDPS of each repeater spans, related with the gradually increased optical link length. And, it is also confirmed that NRD is controlled by postcompensation in optimal optical link with OPC closely placed at WDM receiver.

• Journal of Korean Neurosurgical Society
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• v.59 no.5
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• pp.478-484
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• 2016

Objective : To assess the clinical and radiological factors as predictors for successful outcomes in lumbar disc herniation (LDH) treatment. Methods : Two groups of patients with single level LDH (L4-5) requiring treatment were retrospectively studied. The surgery group (SG) included 34 patients, and 30 patients who initially refused the surgery were included in the nerve blocks group (NG). A visual analogue scale (VAS) for leg and back pain and motor deficit were initially evaluated before procedures, and repeated at 1, 6, and 12 months. Radiological factors including the disc herniation length, disc herniation area, canal length-occupying ratio, and canal area-occupying ratio were measured and compared. Predicting factors of successful outcomes were determined with multivariate logistic regression analysis after the optimal cut off values were established with a receiver operating characteristic curve. Results : There was no significant demographic difference between two groups. A multivariate logistic regression analysis with radiological and clinical (12 months follow-up) data revealed that the high disc herniation length with cutoff value 6.31 mm [odds ratio (OR) 2.35; confidence interval (CI) 1.21-3.98] was a predictor of successful outcomes of leg pain relief in the SG. The low disc herniation length with cutoff value 6.23 mm (OR 0.05; CI 0.003-0.89) and high baseline VAS leg (OR 12.63; CI 1.64-97.45) were identified as predictors of successful outcomes of leg pain relief in the NG. Conclusion : The patients with the disc herniation length larger than 6.31 mm showed successful outcomes with surgery whereas the patients with the disc herniation length less than 6.23 mm showed successful outcomes with nerve block. These results could be considered as a radiological criteria in choosing optimal treatment options for LDH.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.20 no.8
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• pp.746-752
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• 2009

In this paper, we deal with the development of an optimal design program for a triple-band PTFA(Planar Inverted-F Antenna) of 433 MHz, 912 MHz and 2.45 GHz by using evolution strategy. Generally, the resonance frequency of the PIFA is determined by the width and length of a U-type slot used. However the resonance frequencies of the multiple U slots are varied by the mutual effect of the slots. Thus the optimal width and length of U-type slots are determined by using an optimal design program based on the evolution strategy. To achieve this, an interface program between a commercial EM analysis tool and the optimal design program is constructed for implementing the evolution strategy technique that seeks a global optimum of the objective function through the iterative design process consisting of variation and reproduction. The resonance frequencies of the triple-band PIFA yielded by the optimal design program are 430 MHz, 910.5 MHz and 2.458 GHz that show a good agreement to the design target values.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.35 no.8
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• pp.720-725
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• 2007

Cold acoustic tests have been performed to elucidate the effect of baffle gaps on the optimal damping characteristics in a liquid rocket combustor where coaxial injectors are installed. For several axial baffle lengths, an optimal acoustic damping capacitance has been achieved in a certain gap range. Cold acoustic tests for simulating fluid viscosity by changing the pressure in a model chamber have been done to study the main mechanism of optimal damping. Experimental data have shown that the optimal gap for high damping capacity exists mainly due to the viscosity near the gap of baffles. Therefore, axial baffle length can be reduced by using the optimal baffle gap, providing a possible solution of thermal cooling problems. Also, these optimum characteristics can be some guidelines for manufacturing and assembling injectors in full-scaled rocket combustors.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.32A no.2
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• pp.11-18
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• 1995

Error detection in ARQ(Automatic Repeat Request) protocols is very important in wireless data communication systems. The throughput efficiency of ARQ protocols can be improved by dynamically adapting the protocol packet length so that it approaches the optimum value for throuhput efficiency. In this paper, a simple and novel adaptive packet length allocation method is proposed which transmits the packets with variable length by dyanmically estimating the channel codition. The simulation results show that the average of throughput is improved by 315.4% in the stop-and-wait protocol, 41.4% in the go-back-N protocol and 155.9% in the selective repeat protocol respectively. And the throughput performances of adaptive packet length allocation method approximately approach the theoritically optimal throughput performances.

• Journal of the Korean Society of Industry Convergence
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• v.14 no.4
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• pp.167-172
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• 2011

This paper investigated optimal design for slim wall mount arm for flat TV. Recently the number of flat TV sets in use went on increasing in TV market. As the flat TV sets are getting common, consumers came to need another requirements like aesthetic factor besides display performances. As the new TV sets tend to be slimmer due to aesthetic design, Wall mount also requires to be slimmer for aesthetic balance. Slim structures, however, are vulnerable to structural rigidity. In this study, slim wall mount arm has been designed by 3D CAD and DOE (Design of Experiments) and finite element analysis for optimal structural design were carried out to determine the design variables for minimize working stress of wall mount arm. Finally two optimal design conditions were selected through DOE and FEM and one of those was chosen under constraint of minimizing blanking developed length.

• 제어로봇시스템학회:학술대회논문집
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• 2004.08a
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• pp.834-839
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• 2004

In this paper, we investigate the optimal base position and joint configuration of a planar wheeled mobile manipulator in terms of manipulability measure. Taking into account the level of coordination between a manipulator and a platform, both local and global optimization problems are considered. First, based on the kinematic models of a mobile manipulator, the manipulability measures are expressed along with the analysis of the configurational dependency. Second, the geometric symmetry of a mobile manipulator in view of manipulability measure is analyzed, and for some base positions, the best and worst joint configurations are determined, Third, with reverence to the maximum, minimum, and average manipulability measures, the optimal base positions are determined, and the percent improvements due to the base relocation are discussed considering the relative scales among the platform size, the wheel radius, and the link length.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.7A
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• pp.542-549
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• 2005

In this paper, the optimal pump light power of optical phase conjugator (OPC) and the compensation characteristics of distorted WDM channel signals are numerically investigated, when the OPC with highly-nonlinear dispersion shifted fiber (HNL-DSF) not be placed at the mid-way of total transmission length. The total dispersion of former half section and latter half section is assumed to be same each other in this approach. It is confirmed that, in WDM transmission systems with OPC deviated from the mid-way, the pump light power for best compensation must be flexible selected depending on the OPC position. This optimal pump light power is gradually increased as the OPC is gradually closer to the receiver. Consequently, it is possible to establish the compensation system independent on the OPC position by setting optimal pump light power connected with the OPC position.

• Journal of Industrial Technology
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• v.21 no.A
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• pp.59-64
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• 2001

This paper analyzes the performance of the several types of ACL(Asynchronous ConnectionLess) packets used in Bluetooth according to a BER(Bit Error Rate) and a packet length and proposes an optimal packet type and an optimal size of the packet being able to be used under the given BER. This paper proposes how to obtain the optimal packet type and the optimal size of the packet maximizing the performance measure under the given BER. In addition, this paper shows that the optimal type and size of the packet maximizing the throughput are different from those maximizing the mean transmission time. This occurs because the Bluetooth uses not only one type of packet but also various types of packets.