• Journal of Digital Convergence
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• v.12 no.8
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• pp.321-327
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• 2014

Feature selection is the technique to improve the classification performance by using a minimal set by removing features that are not related with each other and characterized by redundancy. This study proposed new feature selection using the distance between the center of gravity of the bounded sum of weighted fuzzy membership functions (BSWFMs) provided by the neural network with weighted fuzzy membership functions (NEWFM) in order to improve the classification performance. The distance-based feature selection selects the minimum features by removing the worst features with the shortest distance between the center of gravity of BSWFMs from the 24 initial features one by one, and then 22 minimum features are selected with the highest performance result. The proposed methodology shows that sensitivity, specificity, and accuracy are 97.7%, 99.7%, and 98.7% with 22 minimum features, respectively.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.39 no.12
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• pp.1055-1061
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• 2002

Conventional TSPC D flip-flop has the advantages of high speed, simple clock distribution, and no racing because of the single phase clocking strategy and its simple structure. But, it suffers from glitch, clock slope sensitivity and unbalanced propagation delay problems. Therefore, a new dynamic D flip-flop, which improves these disadvantages, is proposed. The main idea of this paper is DS(Discharge Suppression) scheme, which suppresses unnecessary discharge. As a result, the proposed structure is free from glitch problem and it improves maximum clock slope immunity from 0.25ns to Ins. Also, it uses only 8 transistors and it Is demonstrated that high speed operation is feasible by balancing propagation delay time.

• Journal of the Earthquake Engineering Society of Korea
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• v.9 no.1 s.41
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• pp.71-78
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• 2005

This paper presents an improved system identification methodology for structural systems by applying static compliance dominant (SCD) frequencies. The existing sensitivity-based system identification technique is extended to adopt the static compliance dominant frequencies, and the performance of the additional spectral information, i.e., SCD frequencies, is compared with that of the natural frequencies only via a numerical example of a mechanical system. The results of the numerical study indicate that the additional use of the SCD frequencies improves accuracy in system identification problems.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.08a
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• pp.186-186
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• 2010

소자의 축소화에 따라 floating gate 형의 flash 메모리 소자는 얇은 게이트 절연막 등의 이유로, 이웃 셀 간의 커플링 및 게이트 누설 전류와 같은 문제점을 지니고 있다. 이러한 문제점을 극복하기 위해 charge trap flash 메모리 (CTF) 소자가 연구되고 있지만, CTF 메모리 소자는 쓰기/지우기 속도와 데이터 보존 성능간의 trade-off 관계와 같은 문제점을 지니고 있다. 최근, 이를 극복하기 위한 방안으로, 다른 유전율을 갖는 유전체들을 적층시킨 터널 절연막을 이용한 Tunnel Barrier Engineered (TBE) 기술이 주목 받고 있다. 따라서, 본 논문에서는 TBE 기술을 적용한 MIS-capacitor를 높은 유전율을 가지는 Al2O3와 HfO2를 이용하여 제작하였다. 이를 위해 먼저 Si 기판 위에 Al2O3 /HfO2 /Al2O3 (AHA)를 Atomic Layer Deposition (ALD) 방법으로 약 2/1/3 nm의 두께를 가지도록 증착 하였고, Aluminum을 150 nm 증착 하여 게이트 전극으로 이용하였다. Capacitance-Voltage와 Current-Voltage 특성을 측정, 분석함으로써, AHA 구조를 가지는 터널 절연막의 전기적인 특성을 확인 하였다. 또한, high-k 물질을 이용한 터널 절연막을 급속 열처리 공정 (Rapid Thermal Annealing-RTA) 과 H2/N2분위기에서 후속열처리 공정 (Post-RTA)을 통하여 전기적인 특성을 개선 시켰다. 적층된 터널 절연막은 열처리를 통해 터널링 전류의 민감도의 향상과 함께 누설전류가 감소됨으로서 우수한 전기적인 특성이 나타남을 확인하였으며, 적층된 터널 절연막 구조와 적절한 열처리를 이용하여 빠른 쓰기/지우기 속도와 전기적인 특성이 향상된 비휘발성 메모리 소자를 기대할 수 있다.

• Proceedings of the Korea Contents Association Conference
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• 2018.05a
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• pp.375-376
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• 2018

본 연구는 20대 성인 손의 감각에 감각입력 훈련시 장악력과 기민성 차이를 알아보고자 하였다. 연구결과 훈련군에서 대조군보다 장악력 및 기민성과 감각역치의 높은 상승률을 나타냈다. 감각입력훈련이 대뇌겉질의 감각수용영역의 크기를 확대시켜 체성 감각시스템의 민감도를 향상시켜 기민성과 감각 향상을 높인 것으로 생각된다. 따라서 근력운동과 감각입력 사이의 적절한 상황 판단을 통한 효율적 사용을 추천한다.

• The Transactions of the Korean Institute of Power Electronics
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• v.4 no.6
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• pp.531-538
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• 1999

This paper proposes a fuzzy logic controller(FLC) for DC-DC converters in order to obtain good l perfonnances that can not be achieved by linear control tc'Chniques in the presence of wide parameter v variations. 'While the standard controller uses error and derivative of e$\pi$or, the proposed controller uses state v variables. Such method is ve$\pi$ efficient in case of DC-DC converters and can guarantee both stable s small-signal responses and improved large signal responses. The presented approach method is general and c can be applied to any dc-dc converter topologies. Through the simulations of booster, we verify the pro[Xlsed C control tc'Chnique can give a satisfactory perfonnance.

• Tuberculosis and Respiratory Diseases
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• v.62 no.3
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• pp.184-191
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• 2007

Background: For the diagnosis of pleural tuberculosis, polymerase chain reaction (PCR) of pleural effusion specimens has shown very low sensitivity, which might be due to the small number of bacilli in the samples. The purpose of this investigation is to determine whether the sensitivity of PCR testing can be improved when increasing the amount of pleural effusion specimens. Methods: We prospectively analyzed pleural effusion specimens obtained from 53 patients for whom the exclusion of the possibility of tuberculous pleural effusion was necessary. We performed Mycobacterium tuberculosis PCR testing using the Cobas Amplicor MTB test (Roche Diagnostic Systems) with three different amounts (10ml, 25ml, and 50ml) of pleural effusion specimen in each patient. Pleural tuberculosis was defined as having one of the following: culture-positive pleural fluid sample, histopathologic finding consistent with tuberculosis on pleural biopsy, culture-positive sputum specimen, and/or positive response to anti-tuberculous medication without other possible causes of pleural effusion. Results: Of the 53 patients, 26 received the diagnosis of pleural tuberculosis. The sensitivities of AFB smearing, Mycobacterium tuberculosis culture of pleural effusion specimen, pleural biopsy, and measurement of ADA were 3.8%, 15.4%, 84.6%, and 88.5%, respectively. The results of PCR testing were positive for 3 (11.5%), 4 (15.4%), and 3 (11.5%) of the 26 patients when using 10ml, 25ml, and 50ml of pleural effusion specimens, respectively. These results did not show a statistically significant difference in the sensitivity of PCR testing when increasing the amount of pleural effusion samples (p>0.05, symmetry exact test). Conclusion: For specimens such as pleural effusion, in which the bacillary load is very low, the clinical utility of PCR testing seems highly limited with the kits designed for the diagnosis of pulmonary tuberculosis. An increased amount of pleural effusion sample does not improve the sensitivity of PCR testing.

• Proceedings of the KWS Conference
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• 2010.05a
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• pp.79-79
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• 2010

저온용 무연 솔더의 대표 조성으로 고려되고 있는 Sn-58Bi(융점: $138^{\circ}C$) 공정(eutectic) 조성은 우수한 강도에도 불구하고 연성(ductility) 측면에서의 문제점이 지속적으로 보고되고 있다. 따라서 이 합금계의 연성을 최대로 개선시킬 수 있으면서도 실제 상용화가 가능한 합금 조성의 개발 연구가 요청된다. 본 연구에서는 Sn-Bi 2원계 조성에서 최대의 연성을 나타내는 것으로 보고된 Sn-40Bi 조성에 미량의 합금원소를 첨가함으로써 최대의 연성을 확보하는 한편, 그 연성 특성이 변형속도에 어느 정도 민감한지를 인장 실험을 통해 결정하고자 하였다. 합금원소로는 0.1~0.5 wt%의 Ag, Mn, In, Cu를 선택하였으며, 인장 시편을 제조하여 $10^{-2}$, $10^{-3}$, $10^{-4}\;s^{-1}$의 3종류로 변형속도를 변형시켜가며 응력-변형 곡선(stress-strain curve)을 측정하였고, 조성별, 변형속도별로 최대인장강도(ultimate tensile stress, UTS) 및 연신율 결과들을 정리하였다. 합금원소를 첨가한 조성의 경우는 모든 시험 조건에서 Sn-40Bi보다 우수한 연신률을 나타내는 것으로 측정되었으나, $10^{-2}\;s^{-1}$의 빠른 변형속도에서는 그 향상 정도가 상대적으로 감소하는 경향이 관찰되었다. 특히 Sn-40Bi-0.5Ag 조성의 경우 느린 변형속도에서 특히 눈에 띄는 연신률 값을 나타내며, 모든 변형속도 조건에서 가장 우수한 연성을 나타내었다. 한편 Sn-40Bi-0.1Cu 조성의 경우 변형속도에 따른 연신률의 변화 정도, 즉, 변형속도에 따른 연신률의 민감도가 매우 커 $10^{-4}\;s^{-1}$ 속도에서는 Sn-40Bi-0.5Ag에 버금가는 연신률 값이 측정되었으나, $10^{-2}\;s^{-1}$ 속도에서는 가장 나쁜 연신률 특성을 보여주었다. Sn-40Bi-0.2Mn 조성은 최고의 연신률 향상 특성을 나타내지는 않았으나, In을 첨가한 경우보다는 대체적으로 우수한 연성을 나타내었다. 이상의 각 합금별 연성 특성은 인장시험 전의 미세조직 관찰 결과와 인장시험 후 파면부의 조직변화 관찰 결과로부터 해석되었다. 그 결과 석출상의 형성 여부, 인장 시험 중 재결정 조직의 형성 여부, 라멜라(lamellar) 조직의 분율과 라멜라 간격(lamellar spacing)의 정도 또는 $\beta$-Sn과 라멜라 조직 사이의 결정립계와 라멜라 조직 내 결정립계에서의 슬라이딩 모드(sliding mode) 변형 정도, 석출상의 크기와 분포 정도 등이 연신률 및 변형속도 민감도와 같은 연성 특성에 가장 큰 영향을 미치는 인자인 것으로 분석되었다.

• Journal of Convergence for Information Technology
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• v.11 no.2
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• pp.98-106
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• 2021

The paper deals with comparative study on sensitivity analysis using various methods regarding to design of experiments for structure design of an active type DSF (Deck support frame) that was developed for float-over installation of offshore plant. The thickness sizing variables of structure member of the active type DSF were considered the design factors. The output responses were defined from the weight and the strength performances. Various methods such as orthogonal array design, Box-Behnken design, and Latin hypercube design were applied to the comparative study. In order to evaluate the approximation performance of the design space exploration according to the design of experiments, response surface method was generated for each design of experiment, and the accuracy characteristics of the approximation were reviewed. The design enhancement results such as numerical costs, weight minimization, etc. via the design of experiment methods were compared to the results of the best design. The orthogonal array design method represented the most improved results for the structure design of the active type DSF.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.33 no.6
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• pp.2293-2302
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• 2013

Flood inundation map has been used as a fundamental information in flood risk management. However, there are various sources of uncertainty in flood inundation mapping, which can be another risk in preventing damage from flood. Therefore, it is necessary to remove or reduce uncertainty sources to improve the accuracy of flood inundation maps. However, the entire removal of uncertainty source may be impossible and inefficient due to limitations of knowledge and finance. Sensitivity analysis of uncertainty sources allows an efficient flood risk management by considering various conditions in flood inundation mapping because an uncertainty source under different conditions may propagate in different ways. The objectives of this study are (1) to perform sensitivity analysis of uncertainty sources by different conditions on flood inundation map using the FOA method and (2) to find a major contributor to a propagated uncertainty in the flood inundation map in Flatrock at Columbus, U.S.A. Result of this study illustrates that an uncertainty in a variable is differently propagated to flood inundation map by combination with other uncertainty sources. Moreover, elevation error was found to be the most sensitive to uncertainty in the flood inundation map of the study reach.