• Structural Engineering and Mechanics
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• 제28권1호
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• pp.107-127
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• 2008

Wind turbine blades are increasing in magnitude without a proportional increase of stiffness for which reason geometrical and inertial nonlinearities become increasingly important. Often these effects are analysed using a nonlinear truncated expansion in undamped fixed base mode shapes of a blade, modelling geometrical and inertial nonlinear couplings in the fundamental flap and edge direction. The purpose of this article is to examine the applicability of such a reduced-degree-of-freedom model in predicting the nonlinear response and stability of a blade by comparison to a full model based on a nonlinear co-rotating FE formulation. By use of the reduced-degree-of-freedom model it is shown that under strong resonance excitation of the fundamental flap or edge modes, significant energy is transferred to higher modes due to parametric or nonlinear coupling terms, which influence the response and stability conditions. It is demonstrated that the response predicted by such models in some cases becomes instable or chaotic. However, as a consequence of the energy flow the stability is increased and the tendency of chaotic vibrations is reduced as the number of modes are increased. The FE model representing the case of infinitely many included modes, is shown to predict stable and ordered response for all considered parameters. Further, the analysis shows that the reduced-degree-of-freedom model of relatively low order overestimates the response near resonance peaks, which is a consequence of the small number of included modes. The qualitative erratic response and stability prediction of the reduced order models take place at frequencies slightly above normal operation. However, for normal operation of the wind turbine without resonance excitation 4 modes in the reduced-degree-of-freedom model perform acceptable.

• 기술혁신학회지
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• 제16권4호
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• pp.1134-1162
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• 2013

본 연구는 우리나라 산업주도기업이 지속적으로 선두위치를 유지하게 하는 혁신전략을 도출하는 것이다. 이를 위해 조선산업의 산업주도권 변천과정을 사례로 연구하였다. 조선산업에서 주도기업이 쇠퇴하는 핵심요인은 현상유지적 경영치중, 급증하는 유력제품에서의 혁신부진, 변화에 저항하는 조직관성인 것으로 나타났다. 시장의 승자는 경쟁력의 우위보다는 변화에 누가 빨리 대응하느냐에 달려 있었고 과거의 성공전략으로는 선두위치를 유지할 수 없음도 밝혀졌다. 주도기업 쇠퇴의 근본원인은 과거의 커다란 성공으로 인해 경쟁상황의 변화에도 기존의 전략을 고집하고 대응을 지연시키는 혁신의 실패에 있었다. 연구결과, 우리나라 산업주도기업이 선두를 유지하기 위한 혁신전략으로 현재의 성공에 안주하지 않고 새로운 변화에 적합한 고객지향형 혁신을 중시하는 경영체계를 구축해야 하는 것과 불황기를 잘 대처하지 못해 재성장의 기회를 상실하였으므로 불황기에 대비한 전략수립 등을 제시하였다. 본 연구가 우리나라 다른 산업의 새로운 전략수립에 기여할 것으로 기대한다.

• 한국의상디자인학회지
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• 제14권3호
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• pp.51-65
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• 2012

This research was conducted to provide basic data for the formulation of marketing strategies suitable to the increasingly globalizing clothing market for the elderly in the fashion industry, by comparing the clothing behavior and preferences of elderly women aged over 70 years in Korea with those of women in the U.S. The 106 questionnaire responses that were collected in the U.S. and the 235 responses that were collected in Korea were used for the analysis, The major objectives of this study were as follow; 1. It was found that the elderly women of Korea utilize mostly human information as information source when purchasing clothing, whereas women of U.S. utilize mostly media information. Comfort was found to be most important factor both countries, but the Korean women considered the aesthetic aspect of clothing more important than did American women. 2. The clothing preference of Korean elderly women aged over 70 years was concentrated in young and feminine images regardless of items, so it could be seen that they had strong desire for looking young. But American elderly women showed different preference depending on items, so it could be seen that they pursue diverse images depending on clothing items and personality without concentrating in one image. The comparison of the preference style by item of elderly women over 70 years of age between Korea and the U,S. showed significant difference. Accordingly, the designs of the clothes of the Korean and American women should be differentiated and developed according to the clothes item and country.

• 한국식품조리과학회지
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• 제23권4호통권100호
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• pp.492-501
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• 2007

This study was conducted to develop a topping formula for pizza containing Chungkukjang and onion as the main ingredients. The maximum amount of onion was limited to 10.5%, since the pizza crust and toppings would separate if too much water dispelled from the onion tissue during baking. The Chungkukjang was substituted for Bulgoggi, a meat topping. The sensory acceptability scores for the pizza topping decreased as the amount of Chungkukjang increased from 3.6% to 7.3%, due to its unpleasant odor, but scores increased when 1.6% Kimchi powder was added to the Chungkukjang without a significant difference from the control. Thus favorable sensory quality was obtained with a topping formula containing 8.7% Chungkukjang, 10.5% onion, and 1.6% Kimchi powder. The nutrient values of the final pizza products were assessed as follows. By adding the Chungkukjang and onion, crude protein, crude lipid, crude ash, and total dietary fiber contents increased. Moreover, the calorie level of the Chungkukjang-onion pizza was 3.8% higher than that of the control pizza. The amounts of compound amino acids including lysine increased. The free amino acids also increased from 143.3 to 188.6 mg/100 g. The ratio of saturated fatty acids to unsaturated fatty acids changed from 1:0.71 to 1:0.81. For the consumer test, the age groups of the participants were classified as 15-29 years old, 30-39 years old, and 40-62 years old. A positive result on acceptability of the developed pizza was obtained from most of the panelists in all age groups. Over 93% of the 119 responding subjects had purchasing intentions. An, especially, strong purchaging intention was shown in the younger age group of 15-29 year-olds, even though they had a lower preference for the Chungkukjang. Finally, an attribute of satisfaction was induced based on 'health' (79.5%) and 'flavor' (15.7%).

• 한국근적외분광분석학회:학술대회논문집
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• 한국근적외분광분석학회 2001년도 NIR-2001
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• pp.3111-3111
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• 2001

The implementation of NIR and chemometrics in the Pharmaceutical industries is still in strong progress, both regarding qualitative and quantitative applications and beneficial results are seen. Looking at the development so far, NIR will change the pharmaceutical industry even more in the future. This presentation will address the experiences and progress achieved regarding the application and implementation of quantitative methods for determination of content uniformity and assay of tablets with less than 10% w/w of active, using Near Infrared transmittance spectroscopy in combination with PLS. Also qualitative methods for identification of the same tablets by Near Infrared reflectance spectroscopy will be discussed. Four commercial tablet strengths are formulated and produced from two different compositions by direct compression. Three different strengths are dose proportional, i.e. fixed concentration by varying in size. The aim was to replace the conventional primary methods for analysing content uniformity, assay and identification by NIR. Studies were performed on comparing transmittance versus reflectance spectroscopy for both applications on the dose proportional tablets. The model for determination of content uniformity and assay was developed to cover both coated and uncoated tablets, whereas the qualitative model was developed to identify coated tablets only. The impact of the tablet formulation, tablet size and coating, resulted in individual models far each composition The best calibration was achieved using diffuse reflectance for the identification purposes and diffuse transmittance for the quantitative determination of the active content within the tablets. As NIR in combination with other techniques opens up the possibility of total quality management within the production, the transfer of the above-mentioned models from a laboratory based approach to an at-line approach at H.Lundbeck will be addressed too.

• Korea-Australia Rheology Journal
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• 제14권1호
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• pp.33-45
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• 2002

Recent results obtained for the port-pom model and the constitutive equations with time-strain separability are examined. The time-strain separability in viscoelastic systems Is not a rule derived from fundamental principles but merely a hypothesis based on experimental phenomena, stress relaxation at long times. The violation of separability in the short-time response just after a step strain is also well understood (Archer, 1999). In constitutive modeling, time-strain separability has been extensively employed because of its theoretical simplicity and practical convenience. Here we present a simple analysis that verifies this hypothesis inevitably incurs mathematical inconsistency in the viewpoint of stability. Employing an asymptotic analysis, we show that both differential and integral constitutive equations based on time-strain separability are either Hadamard-type unstable or dissipative unstable. The conclusion drawn in this study is shown to be applicable to the Doi-Edwards model (with independent alignment approximation). Hence, the Hadamardtype instability of the Doi-Edwards model results from the time-strain separability in its formulation, and its remedy may lie in the transition mechanism from Rouse to reptational relaxation supposed by Doi and Edwards. Recently in order to describe the complex rheological behavior of polymer melts with long side branches like low density polyethylene, new constitutive equations called the port-pom equations have been derived in the integral/differential form and also in the simplifled differential type by McLeish and carson on the basis of the reptation dynamics with simplifled branch structure taken into account. In this study mathematical stability analysis under short and high frequency wave disturbances has been performed for these constitutive equations. It is proved that the differential model is globally Hadamard stable, and the integral model seems stable, as long as the orientation tensor remains positive definite or the smooth strain history in the flow is previously given. However cautious attention has to be paid when one employs the simplified version of the constitutive equations without arm withdrawal, since neglecting the arm withdrawal immediately yields Hadamard instability. In the flow regime of creep shear flow where the applied constant shear stress exceeds the maximum achievable value in the steady flow curves, the constitutive equations exhibit severe instability that the solution possesses strong discontinuity at the moment of change of chain dynamics mechanisms.

• 동의생리병리학회지
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• 제28권3호
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• pp.322-329
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• 2014

The purpose of this study was to investigate the quality of two different commercial Bangpungtongseong-san (BTS) extract granules (BTS-2 and BTS-3) by comparing with BTS decoction (BTS-1). The contents of characterizing components and biological activities of two different commercial BTS extract granules were compared with those of the BTS decoction. The contents of characterizing components were analyzed with HPLC. The antioxidative effects were determined by measuring 2,2-diphenyl-1-picrylhygrazyl (DPPH) radical scavenging and superoxide dismutase (SOD)-like activity. Also, we compared the effects on lipid accumulation and reactive oxygen species (ROS) production during differentiation of 3T3-L1 preadipocytes. The contents of five components except liquiritin and sennoside A were higher in BTS-1. The DPPH radical scavenging and SOD-like activity were higher in BTS-1. BTS-1 significantly inhibited lipid accumulation during differentiation of 3T3-L1 preadipocytes and showed stronger effects than BTS-2, BTS-3. In addition BTS-1 showed stronger inhibition effects on ROS production during differentiation of 3T3-L1 preadipocytes than BTS-2, BTS-3. These results indicate that BTS decoction has strong biological activities than commercial BTS extract granules. It is also consistent with the contents of characterizing components.

• The Plant Pathology Journal
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• 제24권4호
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• pp.453-460
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• 2008

In the course of in vitro and in vivo screening for bioherbicidal agents, a hyphomycete fungus, Myrothecium sp. F0252 was selected as a candidate for the biocontrol of weeds. The isolate was identified as Myrothecium roridum Tode ex. Fries based on the morphological characteristics and 18S ribosomal DNA sequence analysis and registered as Myrothecium roridum F0252. In order to evaluate the in vitro effect of M. roridum F0252 on germination of ladino clover and white clover (Trifolium repens L.) seeds, spore solution of the fungus was employed in two concentrations, $6.5{\times}10^6$ and $2.5{\times}10^7$ spores per mL and then inoculated to the seeds. The fungal spores inhibited the seed germination, infected the seedlings, and caused an abnormal withering and inhibition of seedling growth. In addition, when the herbicidal activity of crude ethyl acetate extract from the liquid culture was assessed on a mini-plant, duck-weed (Lemna paucicostata (L.) Hegelm.), the extract showed high inhibitory effect at the level of $12.5{\mu}g$ per mL. On the other hand, in vivo herbicidal activity of M. roridum F0252 was evaluated by a whole plant spray method. M. roridum F0252 exhibited strong and broad-spectrum herbicidal activity. The herbicidal values ranged from 95-100% against 7 weeds, including Abutilon avicennae and Xanthium strumarium, and 70-80% against Digitaria sanguinalis and Sagittaria pygmaea. When the nutritional utilization (95 carbon sources) pattern of M. roridum F0252 was investigated, it varied with water activity ($a_w$) and temperature conditions, supplying good, basic information in regard to nutritional utilization for proper cultivation and formulation. Our results showed that M. roridum F0252 might be used as a potential biocontrol agent against weedy plants.

• Structural Engineering and Mechanics
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• 제38권1호
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• pp.39-63
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• 2011

Referring to the formulation of physical stochastic optimal control of structures and the scheme of optimal polynomial control, a nonlinear stochastic optimal control strategy is developed for a class of structural systems with hysteretic behaviors in the present paper. This control strategy provides an amenable approach to the classical stochastic optimal control strategies, bypasses the dilemma involved in It$\hat{o}$-type stochastic differential equations and is applicable to the dynamical systems driven by practical non-stationary and non-white random excitations, such as earthquake ground motions, strong winds and sea waves. The newly developed generalized optimal control policy is integrated in the nonlinear stochastic optimal control scheme so as to logically distribute the controllers and design their parameters associated with control gains. For illustrative purposes, the stochastic optimal controls of two base-excited multi-degree-of-freedom structural systems with hysteretic behavior in Clough bilinear model and Bouc-Wen differential model, respectively, are investigated. Numerical results reveal that a linear control with the 1st-order controller suffices even for the hysteretic structural systems when a control criterion in exceedance probability performance function for designing the weighting matrices is employed. This is practically meaningful due to the nonlinear controllers which may be associated with dynamical instabilities being saved. It is also noted that using the generalized optimal control policy, the maximum control effectiveness with the few number of control devices can be achieved, allowing for a desirable structural performance. It is remarked, meanwhile, that the response process and energy-dissipation behavior of the hysteretic structures are controlled to a certain extent.

• Steel and Composite Structures
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• 제27권3호
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• pp.337-353
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• 2018

In previous weak-axis moment connection tests, brittle fracture always initiated near the edge of the beam flange groove weld due to force flow towards the stiffer column flanges, which is the opposite pattern as strong-axis moment connections. As part of the China NSFC (51278061) study, this paper tested two full-scale novel weak-axis reduced beam section moment connections, including one exterior frame connection specimen SJ-1 under beam end monotonic loading and one interior frame joint specimen SJ-2 under column top cyclic loading. Test results showed that these two specimens were able to satisfy the demands of FEMA-267 (1995) or ANSI/AISC 341-10 (2010) without experiencing brittle fracture. A parametric analysis using the finite element software ABAQUS was carried out to better understand the cyclic performance of the novel weak-axis reduced beam section moment connections, and the influence of the distance between skin plate and reduced beam section, a, the length of the reduced beam section, b, and the cutting depth of the reduced beam section, c, on the cyclic performance was analyzed. It was found that increasing three parametric values reasonably is beneficial to forming beam plastic hinges, and increasing the parameter a is conducive to reducing stress concentration of beam flange groove welds while increasing the parameters b and c can only reduce the peak stress of beam flange groove welds. The rules recommended by FEMA350 (2000) are suitable for designing the proposed weak-axis RBS moment connection, and a proven calculation formulation is given to determine the thickness of skin plate, the key components in the proposed weak-axis connections. Based on the experimental and numerical results, a design procedure for the proposed weak-axis RBS moment connections was developed.