• Management Science and Financial Engineering
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• 제5권1호
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• pp.51-71
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• 1999

Performance of the group cumulative sum (CUSUM) control scheme using multiple univariate CUSUM charts is more sensitive to the change of quality control (QC) characteristics than the control chart schemes based on the Hotelling statistic We vexamine three group charts for multivariate normal data sets simulated with various correlation structures and shift directions in the mean vector. These group schemes apply the original measurement vectors, the scaled residual vectors from the re-gression of each variable on all others and the principal component vectors respectively to calculat-ing the CUSUM statistics. They are also compared to the multivariate QC charts based on the Ho-telling statistic by estimating average run lengths, coefficients of variation of run length and ranks in signaling order. On the basis of simulation results, we suggest a control chart scheme appropriate for specific quality control environment.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2006년도 제32회 KOSCO SYMPOSIUM 논문집
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• pp.128-134
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• 2006

A characterization of turbulent reacting flows has proved difficult owing to the complex interaction between turbulence, mixing, and combustion chemistry. There are many types of time scales in turbulent flame which can determine flame structure. This counter jet type premixed burner produces high intensity turbulence. The goal is to gain better insights into the flame structures at high turbulence. 6 propane/air flames gave been studied with high velocity fluctuation in bundle type nozzle and in one hole type nozzle. By measuring velocity fluctuation, turbulent intensity and integral length scale are obtained. And sets of OH LIF images were processed to see flame structure of the mean flame curvatures and flame lengths for comparison with turbulence intensity and turbulent length scales. The results show that the decrease in nozzle size generates smaller flow eddy and mean curvatures of the flame fronts, and a decrease in Damkohler number estimated from flow time scale measurement.

• 한국환경과학회지
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• 제21권8호
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• pp.931-938
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• 2012

The effects were investigated of different lengths and numbers of slitwalls in drainless containers on growth and change in soil moisture volumes on the growth of Diffenbachia amoena 'Marianne' and Begonia rex. Drainless containers filled with amended soil, with square shape ($240mm{\times}240mm$) were used, as well as three different sets of slitwalls (2, 4 or 8, respectively) in addition to non-slitwall containers. Two indoor foliage plants were grown in slitwall containers in randomized blocks with 3 replications in greenhouse conditions, from March to September, 2009. Soil moisture volumes per container were measured by weighing containers every 2 hours during the day. The change in soil moisture volumes showed considerable differences among slitwalls tested in comparison to control containers before and after twice-weekly irrigation. Particularly, the differences in the S2 (195mm, slitwall 2) containers were significantly greater than other containers tested. For Diffenbachia amoena 'Marianne', plant height, length of leaf, dry weight and fresh weight were higher with S2 containers than with those grown in other containers tested. The Begonia rex with the best quality in terms of plant height, length of leaf and width of leaf was grown in S8 (360mm, slitwall 8) containers. Particularly, statistical analysis has indicated that shoot fresh weights of Begonia rex grown in S8 were 3-fold higher than those grown in CS8 containers. The different results obtained within the two species led us to hypothesize a species-specific influence on indoor foliage plant performance. However, plants of both species grown in slitwall containers showed good results compared with plants grown in non-slitwall containers.

• Geomechanics and Engineering
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• 제22권5호
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• pp.397-414
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• 2020

In this paper, practical predictive models for soil shear strength parameters are proposed. As cohesion and internal friction angle are of essential shear strength parameters in any geotechnical studies, we try to predict them via artificial neural network (ANN) and neuro-imperialism approaches. The proposed models was based on the result of a series of consolidated undrained triaxial tests were conducted on reinforced sandy soil. The experimental program surveys the increase in internal friction angle of sandy soil due to addition of polypropylene fibers with different lengths and percentages. According to the result of the experimental study, the most important parameters impact on internal friction angle i.e., fiber percentage, fiber length, deviator stress, and pore water pressure were selected as predictive model inputs. The inputs were used to construct several ANN and neuro-imperialism models and a series of statistical indices were calculated to evaluate the prediction accuracy of the developed models. Both simulation results and the values of computed indices confirm that the newly-proposed neuro-imperialism model performs noticeably better comparing to the proposed ANN model. While neuro-imperialism model has training and test error values of 0.068 and 0.094, respectively, ANN model give error values of 0.083 for training sets and 0.26 for testing sets. Therefore, the neuro-imperialism can provide a new applicable model to effectively predict the internal friction angle of fiber-reinforced sandy soil.

• Bulletin of the Korean Chemical Society
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• 제21권7호
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• pp.720-726
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• 2000

The analytic gradient method for the equation-of-motion coupled-cluster singles and doubles (EOM-CCSD) energy has been extended to employ a reduced molecular orbital (MO) space. Not only the innermost core MOs but also some of the outermost virtua l MOs can be dropped in the reduced MO space, and a substantial amount of computation time can be reduced without deteriorating the results. In order to study the magnitudes and trends of the effects of the dropped MOs, the geometries and vibrational properties of the ground and excited states of BF, CO, CN, N2, AlCl, SiS, P2, BCl, AIF, CS, SiO, PN and GeSe are calculated with different sizes of molecular orbital space. The 6-31 G* and the aug-cc-pVTZ basis sets are employed for all molecules except GeSc for which the 6-311 G* and the TZV+f basis sets are used. It is shown that the magnitudes of the drop-MO effects are about $0.005\AA$ in bond lengths and about 1% on harmonic frequencies and IR intensities provided that the dropped MOs correspond to (1s), (1s,2s,2p), an (1s,2s,2p,3s,3p) atomic orbitals of the first, the second, and the third row atoms, respectively. The geometries and vibrational properties of the first and the second excited states of HCN and HNC are calculated by using a drastically reduced virtual MO space as well as with the well defined frozen core MO space. The results suggest the possibility of using a very smalI MO space for qualitative study of valence excited states.

• 한국수자원학회논문집
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• 제42권9호
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• pp.747-758
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• 2009

본 논문에서는 연속자료로서 세계 최장의 기록을 보유하고 있는 서울지점의 강우량 자료를 이용하여 강우 발생특성의 장기 변동성을 분석하였다. 우선 마코프 연쇄에 근거한 전이확률 및 발생특성을 분석하여 측우기 자료의 정확성을 강우의 발생확률적 측면에서 평가하였다. 그리고 2차원 LOWESS 회귀방법을 이용하여 전이확률의 월간 장기변화특성을 분석하였다. 전이확률 및 발생특성 분석결과 원자료 계열의 CWK와 MRG는 발생특성이 다르게 나타났다. 강우사상의 특성은 과거에 비해 강우사상의 발생빈도가 높아지고 있으며 각 강우사상의 지속기간은 짧아지고 있는 것으로 나타났다. 그리고 전이확률의 월간 장기 변화특성을 분석한 결과, M20을 기준으로 CWK와 MRG의 무강우지속기간은 크게 차이를 보이지 않고 있으며, 강우지속기간은 1830년대 이후 지속적으로 감소하는 경향을 보이고 있는 것으로 나타났다. 특히 최근 9월 강우지속기간의 감소 경향이 두드러지게 나타났다. 이러한 결과를 최근 강우량의 증가양상과 더불어 고려하면 강우사상의 빈도와 심도(강우강도)가 증가하는 추세라고 해석할 수 있다.

• Journal of Korea Trade
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• 제24권2호
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• pp.68-82
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• 2020

Purpose - This study investigates the impact of inland port development in China on the promotion of bilateral trade flows between China and South Korea. Design/methodology - The probable association between the establishment of inland ports and Sino-Korea trade was estimated using gravity models. In this regards, two sets of data were collected. The first dataset consists of the baseline variables of a gravity model, while the second one includes variables of logistics infrastructure development. The indicators of logistics infrastructure development include inland ports, the amount of government expenditure on transport infrastructure, the lengths of roads and railways, the number of trucks and the number of logistics industry workforce. Findings - The results show that inland port development has a positive impact on facilitating bilateral trade between China and South Korea. However, the positive association holds only for Chinese regions with a large trade volume and a proximity to seaports. In other regions, the impact of inland ports is not statistically significant. Originality/value - To the best knowledge of the authors, this study is the first attempt to explore the economic impact of inland ports in China. In addition, the findings in this paper provide both policy and managerial implications for the future development of inland ports, such as the strategic location of inland ports and integrated intermodal operations.

• 한국생활과학회지
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• 제15권6호
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• pp.1049-1062
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• 2006

The purpose of this study is to find out the image according to formative properties of hat and garment in the fashion collection. For the study, the 96 stimuli found frequently in fashion collection from the S/S season of 1998 to the F/W season of 2004 were selected. Sets of stimulus and response scales (7 point semantic) were used as experimental materials. The stimuli were 96 pictures with the types of hat(4), the lengths of hair(3), the types of garment(3), the relations between the color of garment and hat(4), and the materials(4) and patterns of garment(2). The subjects were 415 women college students majoring fashion design related fields and living in Seoul and Gyeongsangnam-do. As statistical methods for data analysis, Factor Analysis, ANOVA test, and LSD test were used. The items of the adjectives were classified into 5 image dimensions; attractiveness, gracefulness, concentration, cuteness, and hardness and softness. Among these factors, each dimensional image was affected by formative properties of hat and garment. The image of a hat-wearer was perceived differently according to the hair style and the formative properties of hat and garment even if the type of hat was same.

• Journal of Biosystems Engineering
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• 제31권6호
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• pp.482-488
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• 2006

Application of precision farming technology to rice cultivation could be an effective measure for rice quality improvement and environment-friendly agriculture. This study was conducted to develope a variable rate pneumatic granule applicator. Previous study reported that application uniformity of the prototype machine (C.V. = 23.3%) was not satisfactory. To improve the uniformity, increase of blow-head number from 12 to 16 was suggested. Analysis of the pneumatic conveying system showed that increase of number of blow-head was possible. Three-way variance analysis of the modified applicator showed that inserting length should be changed according to granule metering rate. The range of metering rate from 27.3 to 417.9 g/s were divided into 4 levels and 4 sets of inserting lengths were determined to ensure CV values less than 15%. The revised applicator showed satisfactory C.V. values of 9.4 to 14.6% in the metering rate. Granule conveying pattern was observed using a high speed camera and judged as the homogeneous flow pattern.

• 설비공학논문집
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• 제25권5호
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• pp.246-254
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• 2013

Some characteristics of nitrogen-water slug flow were optically measured, in vertical acrylic tubes of 2, 5 and 8 mm diameter. Bubble velocity, bubble and unit cell lengths were measured, by analyzing the light intensity signals from two sets of dot laser-infrared sensor modules mounted along the transparent tubes. Optical images of the bubbles were also taken and analyzed, to measure bubble shapes and liquid film thickness. It was found that the measured bubble velocities were in good agreement with the empirical models in the literature, except for those measured under high superficial velocity condition in the 2 mm tube. Bubble length was found to be the longest in the 2 mm tube, being 4 to 5 times those of the other tubes. Liquid film was found to have developed early in the 2 mm tube, which made the blunt shape of the bubble head. Liquid film thickness in the 8 mm tube was measured at almost twice those of the other tubes.