• 한국강구조학회 논문집
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• 제27권1호
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• pp.77-85
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• 2015

본 연구에서는 세장한 부재가 압축력을 받을 경우 발생하는 횡좌굴에 의한 내력의 저하를 방지하기 위해, 좌굴 전에 항복을 유도하는 응력제한장치의 개발에 관한 것으로서, 기존의 면외저항방식 및 슬롯방식과는 상이한 단면절삭방식을 제안하고 그 유효성을 실험적, 해석적으로 규명하고 있다. 단면절삭방식은 단면의 절삭범위에 따라 역학적 특성 및 구조적 성능이 상이한 것으로서, 연구의 대상은 절삭의 폭 및 절삭개수를 주 대상으로 하고 있다. 연구결과, 단면 깊이가 같은 경우 단면 절삭폭의 영향은 나타나지 않았으며, 단면 절삭폭을 좁게, 절삭개수가 많을수록 소성영역에서 좀 더 안정적인 거동을 나타내었다. 따라서, 단면절삭을 이용한 응력제한 장치는 항복 후 안정된 이력거동을 나타내고 있어 응력제한 장치로서 그 유효성이 확인되었으며, 향후 실 구조물에의 적용이 가능하리라 판단된다.

• 전자공학회논문지CI
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• 제48권6호
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• pp.35-46
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• 2011

본 논문에서는 피셔 선형 분리(FLD, Fisher's Linear Discriminant) 기반의 단계적 분류를 이용한 감성 인식 기법을 제안한다. 제안하는 기법은 2종 이상의 감성에 대한 다중 클래스 분류 문제에 대하여, 이진 분류 모델의 연속적인 결합을 통해 단계적 분류 모델을 구성함으로써 복잡도 높은 특징 공간상의 다수의 감성 클래스에 대한 분류 성능을 향상시킨다. 이를 위하여, 각 계층 단계의 학습에서는 감성 클래스들로 이루어진 두 개의 클래스 그룹에 따라 피셔 선형분리 공간을 구성하며, 구성된 공간상에서 Adaboost 방식을 이용하여 이진 분류 모델을 학습하여 생성한다. 각 계층 단계의 학습 과정은 모든 감성 클래스가 구분이 완료되는 시점까지 반복 수행된다. 본 논문에서는 MIT 생체 신호 프로파일을 이용하여 제안하는 기법을 실험하였다. 실험 결과, 8종의 감성에 대한 분류 실험을 통해 약 72%의 분류 성능을 확인하였고, 특정 3종의 감성에 대한 분류 실험을 통해 약 93% 분류 성능을 확인하였다.

• Journal of Microbiology and Biotechnology
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• 제16권4호
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• pp.643-646
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• 2006

Because of potential health hazards of aflatoxins for humans, the present study was conducted to monitor aflatoxin $B_1\;(AFB_1)$ in livestock feeds. A total of 249 samples of feeds collected in Korea were analyzed by DC-ELISA for qualitative analysis of $AFB_1$. Then, 27 samples that were verified to contain $AFB_1$ by DC-ELISA were quantitated by HPLC/FLD. HPLC/FLD analysis revealed that only one sample collected from a farm contained 11 ppb of $AFB_1$, whereas the other samples collected from feed companies did not contain $AFB_1$. The presence of $AFB_1$ was further confirmed by LC/MS analysis. TLC analysis indicated that the result of the DC-ELISA was most likely due to possible contamination of other mycotoxins rather than $AFB_1$. In conclusion, HPLC/FLD analysis following DC-ELISA is necessary for rapid and accurate detection of $AFB_1$.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2007년도 춘계학술대회 논문집
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• pp.258-261
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• 2007

Failure phenomena in uni-axial tension test were experimentally and numerically investigated for AA6111-T4, AA5083-H18 and DP-Steel, which were friction-stir welded with the same and different thicknesses. Forming limit diagram(FLD) was measured using hemispherical dome stretching tests for base materials and also predicted by Hill's bifurcation and M-K theories for welded areas. Finite element simulations well predicted hardening behaviors, failure locations as well as failure patterns for the uni-axial tension tests especially utilizing very fine meshes and FLD along with stress softening.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2009년도 추계학술대회 논문집
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• pp.285-288
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• 2009

The purpose of this study is to predict the forming limit diagram (FLD) of strain-rate sensitive materials on the basis of the Marciniak and Kuczynski (M-K) theory. The strain-rate effect is taken into consideration in such a way that the stress-strain curves for various strain-rates are inputted into the formulation as point data, not as curve-fitted models such as power function. Tensile tests and R-value tests were carried out at several levels of temperature and strain-rate from $25^{\circ}C$ to $300^{\circ}C$ and 0.16 to 0.00016/s, respectively to obtain the mechanical properties of AZ31B magnesium alloy sheet. The FLD of this material was experimentally obtained by limit dome height tests with the punch velocity of 0.1 and 1.0 mm/s at $250^{\circ}C$. The M-K theory-based FLD predicted using Yld2000-2d yield criterion was compared with the experimental results.

• Industrial Engineering and Management Systems
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• 제12권4호
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• pp.389-405
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• 2013

A facility layout design (FLD) problem can be generally introduced as assignment of facilities (departments) to a site such that a set of criteria are satisfied or some objectives are minimized (maximized). Hence, it can be considered as a multi-criteria problem due to the presence of qualitative criteria such as maintenance or flexibility and quantitative criteria such as the total cost of handling material. The VIKOR method was developed to solve multiple criteria decision making problems with conflicting and non-commensurable (different units) criteria, assuming that compromising is acceptable for conflict resolution, the decision maker wants a solution that is the closest to the ideal, and the alternatives are evaluated according to all established criteria. This paper proposes a hierarchical analytic hierarchy process (AHP) and VIKOR approach to solve the FLD problem. A computer-aided layout-planning tool is adopted to generate the facility layout problems, as well as their quantitative data. The qualitative performance measures are weighted by AHP. VIKOR is then used to solve the FLD problem. Finally, the proposed integrated procedure is applied to three real-time examples.

• 한국대기환경학회지
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• 제31권5호
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• pp.482-492
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• 2015

Ground-based measurements were conducted from January 6 to 12 of 2015 for understanding characteristics of nitrogen containing carbonaceous aerosols as 16 amino acids at the Mokpo National University, Korea. The detailed amino acid components such as Cystine ($(SCH_2CH(NH_2)CO_2H)_2$) and Methionine ($C_5H_{11}NO_2S$) and their sources were analyzed by High-Performance Liquid Chromatography with Fluorescence Detection (HPLC-FLD) for behavior of secondary products in particulate matter. In addition, organic carbon (OC) and elemental carbon (EC) based on the carbonaceous thermal distribution (CTD), which provides detailed carbon signature characteristics relative to analytical temperature, and water soluble organic carbon (WSOC) by total organic carbon (TOC) analyzer were used to understand the carbon compound behaviors. The backward trajectories were discussed for originations of carbonaceous aerosols as well. Different airmasses were classified with the amino acids and OC thermal signatures. The results can provide to understand the aging process influenced by the long-range transport from East Sea area.

• 분석과학
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• 제28권6호
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• pp.370-376
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• 2015

Priority pollutant이며 페놀성화합물의 전구체인 페놀을 고체상추출법을 이용하여 추출 정제하여 형광검출기와 질량분석기가 각각 장착된 고속액체크로마토그래프를 이용하여 분석하는 방법을 설정하여 보았다. 고체상추출은 고분자성물질이 충진된 Oasis HLB cartridge를 이용하여 최적의 조건을 확립하였으며 이때의 평균회수율은 87.0% 이었다. 형광검출기를 이용한 경우가 질량분석기를 이용한 경우보다 검출한계가 낮았으나 선택성의 측면에서 질량분석기가 우수하였다.

• 소성∙가공
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• 제20권2호
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• pp.146-153
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• 2011

This study aimed at providing an experimental database for the mechanical properties of AZ31B magnesium alloy sheet such as stress-strain curve, yield stress, R-value and forming limit diagram(FLD) at various strain-rates and temperatures. Tensile tests were carried out on specimens having the orientations of $0^{\circ}$, $45^{\circ}$ and $90^{\circ}$ to the rolling direction with different crosshead speeds in the range between 0.008 and 8 mm/s at temperature from 25(room temperature) to $300^{\circ}C$. The influence of the specimen gage length on the tensile properties was investigated. FLD tests were performed at punch speed of 0.1 and 1.0 mm/s in the same temperature range as that of the tensile tests. Swift cup tests were conducted to verify the usefulness of the material database and the reliability of the finite element analysis(FEA). The effects of strain-rate as well as temperature were taken into account in these simulations. It was shown that the FLD-based failure was reasonably well predicted by the thermal-deformation coupled analysis for this rate-sensitive material.

• 소성∙가공
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• 제16권4호
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• pp.304-308
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• 2007

Failure phenomena in uni-axial tension test were experimentally and numerically investigated for AA6111-T4, AA5083-H18 and DP-Steel, which were friction-stir welded with the same and different thicknesses. Forming limit diagram(FLD) was measured using hemispherical dome stretching tests for base materials and also predicted by Hill's bifurcation and M-K theories for welded areas. Finite element simulations well predicted hardening behaviors, failure locations as well as failure patterns for the uni-axial tension tests especially utilizing very fine meshes and FLD along with stress softening.