• 한국전산구조공학회논문집
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• 제20권3호
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• pp.321-327
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• 2007

본 연구는 탄성균열문제를 신속하고 정확하게 해석할 수 있는 새로운 개념의 그리드(grid) 없는 유한차분법을 제시한다. 이동최소제곱법을 이용한 Taylor 전개식 구성을 통해 직접적인 미분계산 없이 근사함수와 그 미분을 손쉽게 계산한다. 그리드로 인한 절점 간의 종속성이 없어 해석영역 내의 불연속면 모델링이 용이하여 차분식 구성시 균열로 인한 불연속 효과를 고려하는 과정도 자연스럽다. 유한차분법에 근간을 두고 있어 지배 미분방정식을 직접 이산화하기 때문에 수치적분이 필요한 수치기법에 비해 계산속도도 빠르다. 모드 I과 모드 II 균열문제 해석을 통해 본 해석기법이 정확하고 효율적으로 응력확대계수를 계산할 수 있음을 보였다.

• Journal of Ginseng Research
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• 제44권3호
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• pp.413-423
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• 2020

Background: Ginseng berries (GBs) show temporal metabolic variations among different maturation stages, determining their organoleptic and functional properties. Methods: We analyzed metabolic variations concomitant to five different maturation stages of GBs including immature green (IG), mature green (MG), partially red (PR), fully red (FR), and overmature red (OR) using mass spectrometry (MS)-based metabolomic profiling and multivariate analyses. Results: The partial least squares discriminant analysis score plot based on gas chromatography-MS datasets highlighted metabolic disparity between preharvest (IG and MG) and harvest/postharvest (PR, FR, and OR) GB extracts along PLS1 (34.9%) with MG distinctly segregated across PLS2 (18.2%). Forty-three significantly discriminant primary metabolites were identified encompassing five developmental stages (variable importance in projection > 1.0, p < 0.05). Among them, most amino acids, organic acids, 5-C sugars, ethanolamines, purines, and palmitic acid were detected in preharvest GB extracts, whereas 6-C sugars, phenolic acid, and oleamide levels were distinctly higher during later maturation stages. Similarly, the partial least squares discriminant analysis based on liquid chromatography-MS datasets displayed preharvest and harvest/postharvest stages clustered across PLS1 (11.1 %); however, MG and PR were separated from IG, FR, and OR along PLS2 (5.6 %). Overall, 24 secondary metabolites were observed significantly discriminant (variable importance in projection > 1.0, p < 0.05), with most displaying higher relative abundance during preharvest stages excluding ginsenosides Rg1 and Re. Furthermore, we observed strong positive correlations between total flavonoid and phenolic metabolite contents in GB extracts and antioxidant activity. Conclusion: Comprehending the dynamic metabolic variations associated with GB maturation stages rationalize their optimal harvest time per se the related agroeconomic traits.

• 한국농업기계학회:학술대회논문집
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• 한국농업기계학회 2017년도 춘계공동학술대회
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• pp.44-44
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• 2017

The objective of this study was to evaluate firmness, and sweetness index (SI) of tomatoes (Lycopersicum esculentum) by using hyperspectral imaging (HSI) in the range of 1000-1400 nm. The mean spectra of the 95 matured tomato samples were extracted from the hyperspectral images, and the reference firmness and sweetness index of the same sample were measured and calibrated with their corresponding spectral data by partial least squares (PLS) regression with different preprocessing method. The results showed that the regression model developed by PLS regression based on Savitzky-Golay (S-G) second-derivative preprocessed spectra resulted in better performance for firmness, and SI of tomatoes compared to models developed by other preprocessing methods, with correlation coefficients (rpred) of 0.82, and 0.74 with standard error of prediction (SEP) of 0.86 N, and 0.63 respectively. Then, the feature wavelengths were identified using model-based variable selection method, i.e., variable important in projection (VIP), resulting from the PLS regression analyses and finally chemical images were derived by applying the respective regression coefficient on the spectral image in a pixel-wise manner. The resulting chemical images provided detailed information on firmness, and sweetness index (SI) of tomatoes. Therefore, these research demonstrated that HIS technique has a potential for rapid and non-destructive evaluation of the firmness and sweetness index of tomatoes.

• 한국작물학회지
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• 제49권3호
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• pp.211-215
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• 2004

미강에 함유되어 있는 토코페롤 및 토코트리에놀의 함량을 비파괴적으로 신속하게 추정하기 위하여 NIRS(근적외선 분광분석기)를 이용한 분석 방법을 검토하였다. 벼 유전자원 80계통의 미장을 사용하여 HPLC에서 분석된 토코페롤 및 토코트리에놀의 함량치를 NIRS 스펙트럼에 적용시킨 후 검량식을 작성하였다. NIRS의 검량식을 몇가지 방법에 의하여 비교 분석한 결과 2차 미분된 스펙트럼을 MPLS(Modified Partial Least Squares)를 이용한 회귀식에 이용하는 것이 가장 적합하였다. HPLC를 이용한 유전자원들의 성분 함량과 NIRS에서 도출된 검량식과의 상관계수는 토코페롤과 토코트리에놀이 각각 0.992, 0.953을 나타내었다. 이들 검량식은 validation file 에서도 0.846 및 0.956의 높은 상관을 보여 미강 상태에서 토코페롤 및 토코트리에놀의 함량을 NIRS를 이용하여 신속하게 분석할 수 있을 것으로 판단되었다.

• 한국약용작물학회지
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• 제10권5호
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• pp.340-343
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• 2002

삼지구엽초에 함유되어 있는 icariin 함량을 신속하게 추정하기 위하여 NIRS(근적외선 분광분석기)를 이용한 분석 방법을 검토하였다. HPLC를 이용하여 분석된 삼지구엽초 유전자원 150계통에 대한 이카린 함량치를 NIRS 스펙트럼에 적용시켜 42개의 calibration set 와 26개의 valilion set를 구분하였다. NIRS의 검량식을 몇가지 방법에 의하여 비교분석한 결과 2차미분된 스텍트럼을 MPLS(Modified Partial Least Squares)를 이용한 회귀식에 이용하는 것이 가장 적합하였다. HPLC를 이용한 유전자원들의 이카린 함량은 평균 $0.424%(0.12{\sim}0.67%)$이었으며, NIRS에서 도출된 검량식과의 상관계수는 0.951을 나타내었다. 따라서 삼지구엽초의 이카린 함량은 NIRS를 이용하여 신속 편리하게 분석할 수 있음이 인정되었다.

• Journal of the Korean Wood Science and Technology
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• 제44권6호
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• pp.852-863
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• 2016

Wood-plastic composite (WPC) is a promising and sustainable material, and refers to a combination of wood and plastic along with some binding (adhesive) materials. In comparison to pure wood material, WPCs are in general have advantages of being cost effective, high durability, moisture resistance, and microbial resistance. The properties of WPCs come directly from the concentration of different components in composite; such as wood flour concentration directly affect mechanical and physical properties of WPCs. In this study, wood powder concentration in WPC was determined by Fourier transform near-infrared (FT-NIR) and Fourier transform infrared (FT-IR) spectroscopy. The reflectance spectra from WPC in both powdered and tableted form with five different concentrations of wood powder were collected and preprocessed to remove noise caused by several factors. To correlate the collected spectra with wood powder concentration, multivariate calibration method of partial least squares (PLS) was applied. During validation with an independent set of samples, good correlations with reference values were demonstrated for both FT-NIR and FT-IR data sets. In addition, high coefficient of determination (${R^2}_p$) and lower standard error of prediction (SEP) was yielded for tableted WPC than powdered WPC. The combination of FT-NIR and FT-IR spectral region was also studied. The results presented here showed that the use of both zones improved the determination accuracy for powdered WPC; however, no improvement in prediction result was achieved for tableted WPCs. The results obtained suggest that these spectroscopic techniques are a useful tool for fast and nondestructive determination of wood concentration in WPCs and have potential to replace conventional methods.

• 한국근적외분광분석학회:학술대회논문집
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• 한국근적외분광분석학회 2001년도 NIR-2001
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• pp.1511-1511
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• 2001

Energy content, expressed as calories per gram, is an important part of the evaluation and marketing of foods in developed countries. Currently accepted methods of measurement of energy by U.S. food labeling legislation include measurement of gross calories by bomb calorimetry with an adjustment for undigested protein and by calculation using specific factors for the energy values of protein, carbohydrate less the amount of insoluble dietary fiber, and total fat. The ability of NIRS to predict the energy value of diverse, processed and unprocessed cereal food products was investigated. NIR spectra of cereal products were obtained with an NIR Systems monochromator and the wavelength range used for analysis was 1104-2494 nm. Gross energy of the foods was measured by oxygen bomb calorimetry (Parr Manual No. 120) and expressed as calories per gram (CPGI, range 4.05-5.49 cal/g). Energy value was adjusted for undigested protein (CPG2, range 3.99-5.38 cal/g) and undigested protein and insoluble dietary fiber (CPG3, range 2.42-5.35 cal/g). Using a multivariate analysis software package (ISI International, Inc.) partial least squares models were developed for the prediction of energy content. The standard error of cross validation and multiple coefficient of determination for CPGI using modified partial least squares regression (n=127) was 0.060 cal/g and 0.95, respectively, and the standard error of performance, coefficient of determination, bias and slope using an independent validation set (n=59) were 0.057 cal/g, 0.98, -0.027 cal/g and 1.05 respectively. The PLS loading for factor 1 (Pearson correlation coefficient 0.92) had significant absorption peaks correlated to C-H stretch groups in lipid at 1722/1764 nm and 2304/2346 nm and O-H groups in carbohydrate at 1434 and 2076 nm. Thus the model appeared to be predominantly influenced by lipid and carbohydrate. Models for CPG2 and CPG3 showed similar trends with standard errors of performance, using the independent validation set, of 0.058 and 0.088 cal/g, respectively, and coefficients of determination of 0.96. Thus NIRS provides a rapid and efficient method of predicting energy content of diverse cereal foods.

• 한국콘텐츠학회논문지
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• 제17권4호
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• pp.247-255
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• 2017

본 연구는 미분양아파트 구매의사결정에 있어 고려해야하는 특성요인을 규명하고 구매자 유형에 따른 차이를 비교 분석하였다. 구매의사결정에 영향을 미치는 요인을 분석하기 위해 선행연구 고찰을 통하여 특성을 종합하고 PLS(Partial Least Squares)회귀분석을 활용하여 그 영향을 실증하였다. 또한 구매자 유형별 특성을 비교하기 위해 분석대상을 미분양아파트 수요자인 입주자와 공급자인 건설사로 구분하여 설문을 진행하였다. 분석결과 입주자는 내부요인(1.141), 조건완화(1.114), 환경요인(1.107), 사회적 요인(1.048), 외부요인(1.030), 교육환경요인(1.010)의 의사결정요인을 중시하는 것으로 나타났으며 건설사의 경우 사회적 요인(1.401), 환경요인(1.251), 조건완화(1.133)의 의사결정요인이 중요한 것으로 도출되었다. 또한 공통적인 의사결정요인으로 조건완화, 사회적요인, 환경요인이 도출되었다.

• 한국정보통신학회논문지
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• 제21권11호
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• pp.2076-2082
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• 2017

우리나라 스마트폰 이용자는 경제활동 인구의 99% 이상 대부분이 사용하고 있으며 초기 형성단계를 지나 포화상태에 도달한 것으로 전문가들은 내다보고 있다. 본 연구는 지배적 디자인 속성이 스마트폰 사용자의 지속사용의도에 미치는 영향을 알아보고자 하였다. 예측변수로는 확장 기술수용모델에서 제시된 인지된 유용성, 인지된 사용 용이성을 선택하였고 지배적 디자인 속성을 매개 조절변수로 선택하여 개념모델을 완성하였다. 연구대상은 부산경남과 익산전북지역에 거주하는 스마트폰 사용자 135명이며 설문을 통해 기초 데이터를 수집하였다. 인구통계학적인 분석은 IBM SPSS Statistics 19로 하였고 Smart PLS를 사용하여 확인적 요인분석과 변수 간의 인과관계에 대한 경로분석을 실시하였다. 분석결과 지속사용의도에 이르는 모든 경로가 유의미한 영향을 미치는 것으로 나타났다. 또한 지배적 디자인 속성이 태도를 매개하여 조절할 때 지속사용의도는 76% 설명력을 가지는 것으로 나타났다.

• Asia pacific journal of information systems
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• 제14권1호
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• pp.101-123
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• 2004

User satisfaction has been widely used by information system(IS) researchers as the most appropriate surrogate variable for the systems success since Bailey and Pearson(1983) provided their user satisfaction measurement. Because user satisfaction is a perceived performance measure by users, not a real or objective measure for systems success, however, perceived user satisfaction by users may not be exactly identical with the real systems performance. In this regard, if the user's ultimately perceived satisfaction is different from the real systems performance, we need to investigate why these two measures are different and which factors may cause the difference. From the perspective of disconfirmation of user expecations, this study examined why user satisfaction and real systems performance may not be identical each other. Expectaion-disconfirmation theory which has had a central role in marketing in explaining the effects of expectation and disconfirmation on consumer satisfaction was similarly adopted in this study to explain the role of expectation and disconfirmation in user satisfaction in the IS environment. Based on the expectation-disconfirmation theory, the current study developed a research model to examine the effects of expectation, system performance, and disconfirmation on user satisfaction in particular. Six research hypotheses derived from the research model were empirically tested using the partial least squares(PLS) method. The results of the statistical analysis indicate that the effects of system performance and disconfirmation were fairly strong on user satisfaction, while the user's expectation has shown insignificant influences on user satisfaction.