• 한국정보통신학회논문지
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• 제19권4호
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• pp.780-786
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• 2015

SNS 등과 같은 소셜 미디어는 실시간으로 자발적인 고객의 의견들을 대거 포함하고 있어 최근 기업들은 효율적인 경영을 위해 소셜 미디어상의 빅 데이터를 분석하는 시스템을 이용하여 고객피드백에 관한 정보를 수집하고 분석하고 있다. 그러나 온라인 사이트에서 수집한 데이터는 띄어쓰기와 철자 오류가 많아 기존의 형태소 분석기로는 정확한 분석을 할 수 없다. 또한 온라인 상의 문장은 짧다는 특징이 있어 상호 정보량, 카이제곱 통계량 등과 같은 기존의 의미 선택 방법을 이용하게 되면 문장 내 선택 할 수 있는 의미의 부재로 인해 정확한 감성 분류를 할 수 없다는 문제점이 있다. 이러한 문제점들을 해결하기 위해서 본 논문에서는 초/중성 및 어절 패턴 사전을 이용해서 보정할 수 있는 모듈과 문장 내 품사의 우선순위를 이용한 의미 선택 방법을 제안한다. 이러한 방법으로 형태소 분석기에서 추출된 품사 정보를 기반으로 용언과 체언을 분리해서 분석 해당 품사에 종속적인 속성 DB 구축 한 후 학습에 의해 누적된 속성 DB를 사용하여 보다 정확한 긍/부정 감성을 추출한다.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2008년도 춘계학술대회 특별세미나.특별세션
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• pp.27-41
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• 2008

Construction of metro transportation infra is a large-scale project requiring tremendous financial resources. This study suggests operation method to use for rapid transit line existing infra such as Gyeongbu line and spare line capacity following second phase KTX construction. Reviewing various constraints of metro rapid transit operation, we found that the conditions for metro rapid transit operation are already satisfied in Daegu area, just like the case of Gyeongbu line in Seoul Metro area. Also, the evaluation of the economic feasibility of metro rapid transit operation in Daegu area shows that B/C is about 2.4, which implies that there is sufficient economic feasibility. According to the result of sensitivity analysis, the project is economically feasible unless the passenger demand decreases 15% and construction costs increases more than 70%. B/C is evaluated large because the utilization of already exiting infra lowers the initial cost. As one of mass transportation system of large capacity, metro rapid transit can generate significant spillover effect: It will strengthen competitiveness of metro area by connecting cities within the area and by extending one-day life zone of the area, to say nothing of the benefit of improving traffic condition. The construction of metro rapid transit network is necessary for the mass transportation system of Yeongnam area as well as Daegu area, and it may work as a starting point for uniting Daegu and Gyeongbuk and strengthening regional competitiveness.

• Smart Structures and Systems
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• 제10권2호
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• pp.89-110
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• 2012

This study was intended to efficiently perform the probabilistic optimal safety assessment of steel cable-stayed bridges (SCS bridges) using stochastic finite element analysis (SFEA) and expected life-cycle cost (LCC) concept. To that end, advanced probabilistic finite element algorithm (APFEA) which enables to execute the static and dynamic SFEA considering aleatory uncertainties contained in random variable was developed. APFEA is the useful analytical means enabling to conduct the reliability assessment (RA) in a systematic way by considering the result of SFEA based on linearity and nonlinearity of before or after introducing initial tensile force. The appropriateness of APFEA was verified in such a way of comparing the result of SFEA and that of Monte Carlo Simulation (MCS). The probabilistic method was set taking into account of analytical parameters. The dynamic response characteristic by probabilistic method was evaluated using ASFEA, and RA was carried out using analysis results, thereby quantitatively calculating the probabilistic safety. The optimal design was determined based on the expected LCC according to the results of SFEA and RA of alternative designs. Moreover, given the potential epistemic uncertainty contained in safety index, failure probability and minimum LCC, the sensitivity analysis was conducted and as a result, a critical distribution phase was illustrated using a cumulative-percentile.

• 에너지공학
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• 제12권2호
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• pp.93-100
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• 2003

An estimation methodology of the mass and energy (M/E) release due to the main steam line break (MSLB) has been developed with the RETRAN-3D code. In the case of equipment qualification (EQ), the over-estimated temperature would exceed the design limits of some cables or valves. In order to have a more flexible EQ profiles from the MSLB M/E release, the methodology with the best-estimated code was used. The major conditions affecting the MSLB M/E were found to be the initial SG level, heat transfer between primary and secondary sides, power level, operable protection system, main or auxiliary feedwater availability, and break conditions. The RETRAN-3D models were developed for the Kori unit 1 (KRN-1) which is typical two loop Westinghouse (WH) designed plant. Particularly, a detailed model of the steam generators was developed to estimate a more realistic two-phase heat transfer effect of the steam flow. After the modeling, the methodology has been developed through the sensitivity analyses. The M/E release data generated from the analyses have been used as the input to the inside containment pressure and temperature (P/T) analysis. According to the results at the point of view containment P/T, the Kori unit 1 can have more margin of 5∼15 ㎪ in pressure and 8∼15$^{\circ}C$ in temperature.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1994년도 하계학술대회 논문집 A
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• pp.208-210
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• 1994

In this paper, the design sensitivity evaluation based on the 2-dimensional finite clement discretization is presented for the voltage source and eddy current problem. And it is applied to the two shape design problems of the rotor slot of 3-phase squirrel cage induction motors. The first is to increase the starting torque while keeping the rated torque fixed. The other is only to increase the torque at the rated speed while keeping the starting torque fixed. As an optimization method, the Gradient Projection method is used to control casily the torques for various speeds of rotor. One fourth of rotor is analyzed by using a semi-periodic boundary condition. Because the shape of rotor slot has much influence on the slip torque characteristic, the 10 design parameters are taken on the interface between rotor core and rotor bar. The initial shape of rotor slot is the trapezoidal typo with rounding corners.

• 항공우주시스템공학회지
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• 제18권2호
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• pp.71-78
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• 2024

초기 열설계 과정의 경우 복잡한 궤도 열 환경 조건에서 다양한 설계 변수에 따른 열적 영향성 판단을 해야 하므로, 열 설계/분석에 많은 시간이 소요된다. 따라서, 초기 설계 단계에서 시간을 효율적으로 단축시키기 위해서는 최적의 설계 변수 도출과 이에 따른 온도 예측이 신속히 이루어져야 한다. 상기 문제점에 기인하여 차수축소모델을 활용한 최적 설계 전문 소프트웨어인 Veritrek이 2018년에 출시되었다. 본 논문에서는 Veritrek 소프트웨어를 활용하여 그라파이트시트 기반 냉각기 열 제어 시스템에 대해 차수축소모델 구축과 민감도 분석, 최적 설계 분석을 수행하여 냉각기의 허용온도를 만족할 수 있는 그라파이트시트의 적층 수, 방열판 면적 및 두께에 대한 최적설계 수치를 도출하였다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제44회 동계 정기학술대회 초록집
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• pp.243-244
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• 2013

Over the past 15 years, several groups have incorporated radio-frequency quadrupole (RFQ) based instruments before the accelerator in accelerator mass spectrometry (AMS) systems for ion-gas interactions at low kinetic energy (＜40 eV). Most AMS systems arebased on a tandem accelerator, which requires negative ions at injection. Typically, AMS sensitivity abundance ratios for radioactive-to-stable isotope are limited to Xr/Xs ＞10^-15, and the range of isotopes that can be analyzed is limited because of theneed to produce rather large negative ion beams and the presence of atomic isobaric interferences after stripping. The potential of using low-kinetic energy ion-gas interactions for isobar suppression before the accelerator has been demonstrated for several negative ion isobar systems with a prototype RFQ system incorporated into the AMS system at IsoTrace Laboratory, Canada (Ontario, Toronto). Requisite for any such RFQ system applied to very rare isotope analysis is large transmission of the analyte ion. This requires proper phase-space matching between the RFQ acceptance and the ion beam phase space (e.g. 35 keV, ${\varphi}3mm$, +-35 mrad), and the ability to control the average ion energy during interactions with the gas. A segmented RFQ instrument is currently being designed at Korea Institute for Science and Technology (한국과학기술연구원, KIST). It will consist of: a) an initial static voltage electrode deceleration region, to lower the ion energy from 35 keV down to ＜40 eV at injection into the first RFQ segment; b) the segmented quadrupole ion-gas interaction region; c) a static voltage electrode re-acceleration region for ion injection into a tandem accelerator. Design considerations and modeling will be discussed. This system should greatly lower the detection limits of the 6 MV AMS system currently being commissioned at KIST. As an example, current detection sensitivity of 41Ca/Ca is limited to the order of 10^-15 while the 41Ca/Ca abundance in modern samples is typically 41Ca/Ca~10^-14 - 10^-15. The major atomic isobaric interference in AMS is 41K. Proof-of-principal work at IsoTrace Lab. has demonstrated that a properly designed system can achieve a relative suppression of KF3-/41CaF3- ＞4 orders of magnitude while maintaining very high transmission of the 41CaF3- ion. This would lower the 41Ca detection limits of the KIST AMS system to at least 41Ca/Ca~10^-19. As Ca is found in bones and shells, this would potentially allow direct dating of valuable anthropological archives and archives relevant to our understanding of the most pronounced climate change events over the past million years that cannot be directly dated with the presently accessible isotopes.

• 한국군사과학기술학회지
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• 제7권4호
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• pp.70-78
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• 2004

A study has been made to investigate the high temperature deformation behavior of Ti-6Al-4V alloyand to predict the final microstructure under given forming conditions. Equiaxed and $Widmanst\ddot{a}tten$ microstructures of Ti-6Al-4V alloys were prepared as initial microstructures. By performing the compression tests at high temperatures$(700\~1100^{\circ}C)$ and at a wide range of strain rates$(10^{-4}\~10^2/s)$, various parameters such as strain rate sensitivity(m) and activation energy(Q) were calculated and used to establish constitutive equations. When the specimens were deformed up to strain 0.6, equiaxed microstructure did not show any significant changes in microstructure, while $Widmanst\ddot{a}tten$ microstructure revealed considerable flow softening, which was attributed to the globularization of a platelet at the temperature range of $800\~970^{\circ}C$ and at the strain rate range of $10^{-4}\~10^{-2}/s$. To predict the final microstructure after forming, finite element analysis was performed considering the microstructural evolution during the deformation. The grain size and the volume fraction of second phase of deformed body were predicted and compared with the experimental results.

• Asian Pacific Journal of Cancer Prevention
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• 제15권12호
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• pp.4933-4938
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• 2014

Background: Although various tumor markers have been utilized in management of stomach cancer (SC), only a few reports have described relevance of examples such as CYFRA 21-1 and neuron-specific enolase (NSE). The purpose of this study was to evaluate the potential diagnostic performance of carcinoembryonic antigen (CEA), CA 19-9, CA72-4, CYFRA 21-1 and NSE in patients with SC. Materials and Methods: Ninety-six SC patients with pathologic confirmation between 2012 and 2013 were enrolled. Serum levels of five tumor markers were analyzed using a solid-phase immunoradiometric assay. Receiver operating characteristic (ROC) curves were plotted for the five tumor markers to investigate their diagnostic powers and adjusted cutoff values derived from analysis of ROC curves were evaluated to calculate the sensitivity of each for SC with recommended cutoff values. Results: Based on two different cutoff values (recommended and adjusted), CYFRA 21-1 (${\geq}2.0$ and 1.2 ng/ml) had a respective sensitivity of 50% and 78.1%, compared with 8.3% and 18.8% for CEA (${\geq}7.0$ and 3.9 ng/ml), 15.6% and 18.8% for CA 19-9 (${\geq}37$ and 26.7 ng/ml), 28.1% and 9.6% for CA 72-4 (${\geq}4.0$ and 13 ng/ml) and 7.3% and 7.3% for NSE (${\geq}14.7$ and 15.0 ng/ml) in the initial staging of primary SC. The area under the curve (AUC) for CYFRA 21-1, with a value of 0.978 (95% confidence interval, 0.964-0.991) was comparatively the highest. Univariate analysis revealed significant relationships between tumor marker level and lymph node involvement, metastasis and staging with CYFRA 21-1, CA 72-4 and NSE. Conclusions: CYFRA 21-1 was the most sensitive tumor marker and showed the most powerful diagnostic performance among the five SC tumor markers. NSE and CA 72-4 are significantly related to lymph node involvement, metastasis or stage. Further evaluations are warranted to clarify the clinical usefulness and prognostic prediction of these markers in SC.

• Korean Journal of Radiology
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• 제22권7호
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• pp.1185-1193
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• 2021

Objective: Clear cell sarcoma of the kidney (CCSK) is the second-most common but extremely rare primary renal malignancy in children after Wilms' tumor. The aims of this study were to evaluate the imaging features that could distinguish between CCSK and Wilms' tumor and to assess the features with diagnostic value for identifying CCSK. Materials and Methods: We reviewed the initial contrast-enhanced abdominal-pelvic CT scans of children with CCSK and Wilms' tumor between 2010 to 2019. Fifty-eight children (32 males and 26 females; age, 0.3-10 years), 7 with CCSK, and 51 with Wilms' tumor, were included. The maximum tumor diameter, presence of engorged perinephric vessels, maximum density of the tumor (Tmax) of the enhancing solid portion, paraspinal muscle, contralateral renal vein density, and density ratios (Tmax/muscle and Tmax/vein) were analyzed on the renal parenchymal phase of contrast-enhanced CT. Fisher's exact tests and Mann-Whitney U tests were conducted to analyze the categorical and continuous variables, respectively. Logistic regression and receiver operating characteristic curve analyses were also performed. Results: The age, sex, and tumor diameter did not differ between the two groups. Engorged perinephric vessels were more common in patients in the CCSK group (71% [5/7] vs. 16% [8/51], p = 0.005). Tmax (median, 148.0 vs. 111.0 Hounsfield unit, p = 0.004), Tmax/muscle (median, 2.64 vs. 1.67, p = 0.002), and Tmax/vein (median, 0.94 vs. 0.59, p = 0.002) were higher in the CCSK compared to the Wilms' group. Multiple logistic regression revealed that engorged vessels (odds ratio 13.615; 95% confidence interval [CI], 1.770-104.730) and Tmax/muscle (odds ratio 5.881; 95% CI, 1.337-25.871) were significant predictors of CCSK. The cutoff values of Tmax/muscle (86% sensitivity, 77% specificity) and Tmax/vein (71% sensitivity, 86% specificity) for the diagnosis of CCSK were 1.97 and 0.76, respectively. Conclusion: Perinephric vessel engorgement and greater tumor enhancement (Tmax/muscle > 1.97 or Tmax/vein > 0.76) are helpful for differentiating between CCSK and Wilms' tumor in children aged below 10 years.