• The Mathematical Education
• /
• v.44 no.2 s.109
• /
• pp.307-323
• /
• 2005

The purpose of this study was to develop a program to cultivate mathematical creativity based on open-ended problem and to investigate its effect. The major features of this innovative program are (a) breaking up fixations, (b) multiple answers, (c) various strategies, (d) problem posing, (e) exploring strategies, (f) selecting and estimating, (g) active exploration through open-ended problems. 20 units for 7th grade mathematics were developed. This study hypothesizes that experimental students may develop more divergent thinking abilities than their traditional counterparts. The participants were 7th grade students attending middle schools in Seoul. Instruments were pre and post tests to measure mainly divergent thinking skills through open-ended problems. The results indicated that the experimental students achieved better than the comparison students on overall and each component of fluency, flexibility, and originality of divergent thinking skills, when deleting the effect of covariance of the pretest. The developed program can be a useful resource for teachers to use in enhancing their students' creative thinking skills. Further this open-ended approach can be served as a model to implement in classes. This study suggests that further investigations are needed in order to examine effects on affective domains such as motivation and task perseverance which are also considered as important factors of creativity.

• Molecules and Cells
• /
• v.40 no.11
• /
• pp.837-846
• /
• 2017

As a component of the neurovascular unit, cerebral smooth muscle cells (CSMCs) are an important mediator in the development of cerebral vascular diseases such as stroke. Epoxyeicosatrienoic acids (EETs) are the products of arachidonic acid catalyzed by cytochrome P450 epoxygenase. EETs are shown to exert neuroprotective effects. In this article, the role of EET in the growth and apoptosis of CSMCs and the underlying mechanisms under oxygen glucose deprivation (OGD) conditions were addressed. The viability of CMSCs was decreased significantly in the OGD group, while different subtypes of EETs, especially 14,15-EET, could increase the viability of CSMCs under OGD conditions. RAPA (serine/threonine kinase Mammalian Target of Rapamycin), a specific mTOR inhibitor, could elevate the level of oxygen free radicals in CSMCs as well as the anti-apoptotic effects of 14,15-EET under OGD conditions. However, SP600125, a specific JNK (c-Jun N-terminal protein kinase) pathway inhibitor, could attenuate oxygen free radicals levels in CSMCs as well as the anti-apoptotic effects of 14,15-EET under OGD conditions. These results strongly suggest that EETs exert protective functions during the growth and apoptosis of CSMCs, via the JNK/c-Jun and mTOR signaling pathways in vitro. We are the first to disclose the beneficial roles and underlying mechanism of 14,15-EET in CSMC under OGD conditions.

• ALGAE
• /
• v.22 no.3
• /
• pp.247-252
• /
• 2007

Crude fucoidan was extracted from the sporophyll of Korean Undaria pinnatifida collected at a coastal area ofWando, Korea, mainly by dilute acid extraction, ethanol precipitation, CaCU Precipitation, with an yield of approxi-mately 3.9% in mass. It was further purified by DEAE-cellulose column chromatography and its chemical composi-don and in vitro anticoagulant activity was determined. The average molecular mass of the purified fucoidan wasestimated about 2.1 x 103 kDa by size-fractionation HPLC and it consisted of neutral sugar (52.34% in mass), uronicacid (26.2%), and sulfate esters (7.4%). From the HPAEC-PAD analysis, the monosaccharide composition of thepurified fucoidan was shown to be fucose, galactose, xylose, and mannose, with a molar ratio of 1, 0.2, 0.02, 0.15,respectively, demonstrating that major monosacd-iande was fucose (72.3% in mol percentage) and other sugars,xylose (1.5%), galactose (14.6%), and mannose (10.9%) were present as minor component. The results suggested thatthis fucoidan is a sulfated, U-type fucoidan. The activated partial thrombloplastin time (APTT) assay of the purifiedfucoidan showed that the purified fucoidan elicited anticoagulant activity in a dose-dependent manner. Five jUg ofsporophyll fucoidan delayed the blood clotting time up to 5 times than untreated control and also up to 1.5 timesthan the same amount of the commercial fucoidan, respectively. Although it is preliminary, these results suggestthat the fucoidan of Korean Undaria vinnatifida sporophyll would be promising candidates for the development ofan anticoaeulant.

• Journal of Advanced Marine Engineering and Technology
• /
• v.34 no.2
• /
• pp.325-331
• /
• 2010

In this study, highly miniaturized short-wavelength meander line employing eriodically patterned ground structure (PPGS) was developed for application to miniaturized on-chip passive component on GaAs MMIC (monolithic microwave integrated circuit). The meander line employing PPGS showed shorter wavelength and slow-wave characteristic compared with conventional meander line. The wavelength of the meander line employing PPGS structure was 17 % of the conventional meander line on GaAs MMIC. Due to its slow-wave structure, the meander line employing PPGS exhibited large propagation constant than conventional meander line, which resulted in larger phase shift and shunt inductance value. Above results indicate that the meander line employing PPGS is a promising candidate for application to a development of miniaturized on-chip RF components as well as inductor with a high inductance value on GaAs MMIC.

• The Korean Journal of Food And Nutrition
• /
• v.19 no.4
• /
• pp.381-391
• /
• 2006

The rheological properties of dough made the substitution of wheat flour(composite flour) at the levels of 0%, 5%, 10% and 15% soymilk residue flour, with addition of vital wheat gluten at the levels of 3, 6 and 9% were investigated. And nutrition contents of soymilk residue flour were analyzed. The results were as follows; Principal components of soymilk residue flour were 22.0% crude protein, 13.2% crude lipid, 54.3% carbohydrate, 27.2% dietary fiber and $220{\mu}g/g$ isoflavones. Free amino acid component of soymilk residue were L-glutamic acid, L-leucine, L-lysine, L-valine, L-phenylalanine, L-isoleucine, L-threonine, L-methionine and L-cystine. Total dietary fiber content of bread with soymilk residue and wheat flour were 5% soymilk residue; 3.50%, 10% soymilk residues; 4.65%, 15% soymilk residues; 5.96%, and wheat flour bread: 2.1% respectively Mixing water absorption capacity was increased by increasing amounts of added soymilk residue and vital wheat gluten. Dough development time was increased by increasing amounts of added soymilk residues, while decreased by increasing amounts of vital wheat gluten. The dough volume of composite flour with 5%, 10% and 15% soymilk residue flour were the smaller than wheat flour dough. But the dough volume was increased by added vital wheat gluten, and the composite flour with 5% soymilk residue flour and 9% vital wheat gluten was better than the others. This study proved that the dough volume of composite flour with 5% soymilk residue flour and 9% vital wheat gluten was better than the others. On the other hand, the soymilk residue flour contains dietary fiber, isoflavone, protein, lipid and carbohydrate. Therefore the soymilk residue flour will be very useful as food material.

• Journal of IKEEE
• /
• v.19 no.3
• /
• pp.440-446
• /
• 2015

This study has examined susceptibility of LNA(Low Noise Amplifier) due to Front-Door Coupling under Narrow-Band high power electromagnetic wave. M/DFR(Malfunction/Destruction Failure Rate) was measured to investigate the diagnostic of IC test. In addition, decapsulation analysis was used to understand the inside of the chip state in LNA devices. The experiments is employed as an open-ended waveguide to study the destruction effects of LNA using a 2.45 GHz Magnetron as a high power electromagnetic wave. The susceptibility level of LNA was assessed by electric field strength, and its failure modes were observed. The malfunction of LNA device has showed as the type of self-reset and power-reset. The electric field strength of malfunction threshold is 524 V/m and 1150 V/m respectively. Also, he electric field of destruction threshold is 1530 V/m. Three types of damaged LNA were observed by decapsulation analysis: component, onchipwire, and bondwire destruction. Based on these results, the susceptibility of the LNA can be applied to a database to help elucidate the effects of microwaves on electronic equipment.

• Industry Promotion Research
• /
• v.2 no.1
• /
• pp.1-7
• /
• 2017

In the case of manufacturing companies, various types of data are collected. Many of these data can be used as useful information for product reliability evaluation. In this study, we first look at data that can be collected by a manufacturing company and related to products, technology, finance, and customers. Next, we will look at the company's business management system, scientific journals, test and marketing survey data, etc., as sources of data. Next, look at what kind of data is collected over the product life cycle to evaluate the reliability of the product. In the development stage of the product, reliability test is performed for each component, and reliability data is collected by performing reliability test at the subsystem and system level. On the other hand, at the manufacturing stage, data on the functional test and the design change test of the product are collected, and at the field stage, the problem of the product is detected in the field and collected in the form of data. Finally, let's look at what you need to do to make a reasonable analysis later in your data collection.

• Clean Technology
• /
• v.9 no.1
• /
• pp.9-21
• /
• 2003

CFC-113 and 1,1,1-TCE which are ozone destruction substances are not used any more in the advanced countries because of Montreal protocol. MC and TCE are now used restrictively at small part of industrial fields in most of countries since they are known to be hazardous or carcinogenic materials. Thus, it is indispensible that the alternative cleaning agents which are environmental-friendly and safe, and show good cleaning ability should be developed or utilized for replacement of the halogenated cleaning agents. Aqueous cleaning agents are evaluated to be promising alternative ones among various alternatives in environmental and economical view point. This study has been carried out as a part of development program of aqueous cleaning agent. First of all, several types of surfactants which are the most important component in aqueous cleaning agents were chosen, and the physical properties, foaming ability, cleaning ability and oil-water separation efficiency of their aqueous solutions were measured and compared for selection of proper type of surfactant in aqueous cleaning agents.

• Korean Journal of Agricultural Science
• /
• v.40 no.4
• /
• pp.395-403
• /
• 2013

Plant factory has drawn attention in many countries in the world due to capability of environmental control not only for better yield and quality, but also for increase in functional and medicinal components of the products. In this paper, an experimental plant factory was constructed for various tests under different environmental conditions, and the operations were evaluated. A production room was constructed with adiabatic materials with dimensions of $6,900{\times}3,000{\times}2,500$ mm ($L{\times}W{\times}H$). Four sets of $2,890{\times}600{\times}2,320$ mm ($L{\times}W{\times}H$) production frame unit, each with 9 light-installed beds and an aeroponic fertigation system, resulting in 36 beds, were prepared. Accuracy and response were evaluated for each environmental control component with and without crops. Air temperature, humidity, $CO_2$ concentration, light intensity, frequency, and duty ratio, fertigation rate and scheduling were controllable from a main control computer through wireless communication devices. When the plant factory was operated without crop condition, the response times were 8 minutes for change in temperature from 20 to $15^{\circ}C$ and 20 minutes from 15 to $20^{\circ}C$; 7 minutes for change in humidity from 40 to 65%; and 4 minutes for change in $CO_2$ concentration from 450 to 1000 ppm. When operated for 24 hours with crop cultivation; average, maximum, and minimum values of temperatures were 20.06, 20.8, and $18.8^{\circ}C$; humidity were 66.72, 69.37, and 63.73%; $CO_2$ concentrations were 1017, 1168, and 911 ppm, respectively. Photosynthetic Photon Flux Density was increased as the distance from the light source decreased, but variability was greater at shorter distances. Results of the study would provide useful information for efficient application of the plant factory and to investigate the optimum environment for crop growth through various experiments.

• Journal of the Society of Naval Architects of Korea
• /
• v.55 no.1
• /
• pp.9-21
• /
• 2018

Survivability of naval vessels is defined as the ability to perform functions and missions in a combat environment. Survivability has close relationship with the spatial layout of naval vessels. In order to maximize survivability, it must be considered from the early stage of design. However the existing concept of survivability was intended to be applied to unit vessels. So it was not suitable for assessment of spatial layout results at the early stage of design. In this paper, a simplified assessment method which can evaluate the spatial layout considering the survivability in the early stage of design has been proposed. For this, assessment layers were defined on survivability components such as susceptibility, vulnerability, and recoverability. Assessment layers of each component were overlapped to deduce a survivability layer of spatial layout alternatives. In addition, the proposed method and optimization algorithm were used to derive optimal spatial layout alternatives considering survivability.