• Journal of the Institute of Electronics Engineers of Korea SD
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• v.40 no.1
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• pp.1-10
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• 2003

Device characteristics of the Metal-Ferroclecric-Semiconductor FET(MFSFET) are simulated in this study. The field-dependent polarization model and the square-law FET model are employed in our simulation. C-V$_{G}$ curves generated from our MFSFET simulation exhibit the accumulation, the depletion and the inversion regions clearly. The capacitance, the subthreshold and the drain current characteristics as a function of gate bias exhibit the memory windows are 1 and 2 V, when the coercive voltages of ferroelectric are 0.5 and 1 V respectively. I$_{D}$-V$_{D}$ curves are composed of the triode and the saturation regions. The difference of saturation drain currents of the MFSFET device at the dual threshold voltages in I$_{D}$-V$_{D}$ curve is 1.5, 2.7, 4.0, and 5.7 ㎃, when the gate biases are 0, 0.1, 0.2 and 0.3V respectively. As the drain current is demonstrated after time delay, PLZT(10/30/70) thin film shows excellent reliability as well as the decrease of saturation current is about 18 % after 10 years. Our simulation model is expected to be very useful in the estimation of the behaviour of MFSFET devices.T devices.

• Korean Journal of Soil Science and Fertilizer
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• v.49 no.3
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• pp.235-241
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• 2016

The soil does not only serve as a medium for plant growth but also for engineering construction purposes. It is very weak in tension, very strong in compression and fails only by shearing. The behaviour of the soil under any form of loading and the interactions of the earth materials during and after any engineering construction work has a major influence on the success, economy and the safety of the work. Soils and their management have therefore become a broad social concern. A limitless variety of soil materials are encountered in both agronomy and engineering problems, varying from hard, dense, large pieces of rock through gravel, sand, silt and clay to organic deposits of soft compressible peat. All these materials may occur over a range of physical properties, such as water contents, texture, bulk density and strength of soils. Therefore, to deal properly with soils and soil materials in any case requires knowledge and understanding of these physical properties. The desired value of bulk density varies with the degree of stability required in construction. Bulk density is also used as an indicator of problems of root penetration,soil aeration and also water infiltration. This property is also used in foundation engineering problems. While not conforming to standard test procedures, this work attempts to add to the basic information on such important soil parameters as water content, bulk density.

• Journal of Biomedical Engineering Research
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• v.19 no.5
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• pp.495-502
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• 1998

A mathematical model of viscoelasticity on the material property of human pharyngeal tissue utilizing Y.C. Fung's Quasi-linear viscoelastic theory is proposed based on cyclic load, stress relaxation, incremental load, and uniaxial tensile load tests. The material properties are characterized and compared with other biological materials' results. The mathematical model is proposed by combining two characteristic functions determined from the stress relaxation and uniaxial tensile load tests. The reduced stress relaxation function G(t) and elastic response function S(t) are obtained from stress relaxation test and uniaxial tensile load test results respectively. Then the model describing stress-time history of the tissue is implemented utilizing two functions. The proposed model is evaluated and validated by comparing the model's cyclic behaviour with experimental results. The model data could be utilized as an important information for constructing 3-dimensional biomechanical model of human pharynx using FEM(Finite Element Method).

• Korean Journal of Community Nutrition
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• v.13 no.3
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• pp.386-395
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• 2008

Since obesity has been a crucial issue regarding children's health in Korea, numerous studies have been conducted. However, it is difficult to locate studies that can help researchers and/or medical professionals who want to study behavioral differences between obese and normal weight (non-obese) children. The collected literature about obese childrens behaviors were accumulated by performing 'key word' searches from several web engines: 'obesity' 'children obesity' 'behavior' 'habit' 'eating behavior or habit' 'exercise' 'physical activity' and 'daily behavior'. The information was extracted and the behaviors were reviewed utilizing 30 papers that revealed any differences from normal weight children with at least p .05 level of significance. According to those studies, the obese children tended to skip meals more often as a method of losing weight. They also have an increased appetite, eat larger portions and rarely leave food on their plates. The obese children prefer to eat high fat, high calorie foods and eat faster than their normal weight counterparts. Also, the children usually eat alone and eat at irregular meal times. Beside the behaviors related to the standard three meals a day, obese children have high preferences for snacking. The children reported that with pocket money they usually eat certain types of snacks without parent approval. The children stated that they exercise more on a regular basis. However, when asked about their participation they were not likely to engage actively. Meanwhile, they tend to spend free time doing sedentary activities such as watching TV or playing on the computer. Since these studies used self -reported questionnaires with a small sample, size there may be difficulty in forming a basis about obese children's behaviors. Nevertheless, these findings are in accordance with other studies conducted in local as well as western countries. In conclusion, obese children have different daily behaviors or routines from normal weight children. It is recommended that altering these behavioral patterns to match those of normal weight children should be encouraged.

• Journal of Korea Technology Innovation Society
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• v.11 no.2
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• pp.171-193
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• 2008

Every country of the world in the 21st century is going to push forward the policy protecting their intellectual property right, and international movement to protect their intellectual right is still more strengthened. Under these situations, the firm is required to seek for more efficient methods of technology security and business management while the existence of business itself is at risk. The control of intellectual properties in business should be considered in the patent management. In the company, the industrial property right should be into one of the management resource, and its importance has great influence on the existence of the company. The information in patent data can be used for strategic planning purposes. This study systematically evaluates the patenting behaviour of sample of 27 business firms within the Korean metal industry. Utilizing the patent application data between 2000 and 2005, the relationship between these patenting management and company performance is analysed. This study showed that patent activity per employee and labor productivity are positive relationship, but patent activity per employee and firm size are negative relationship. Since a positive relationship between patenting and company performance could be shown, patent activity gains important as a instrument for R&D planning.

• Journal of the Mineralogical Society of Korea
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• v.18 no.1
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• pp.53-59
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• 2005

Rb-Sr isotopic ages of oxidized biotite in the weathering profile of granodiorite, Yecheon area, were measured by thermal ionization mass spectrometry, and compared with their K-Ar ages. A decrease of Rb-Sr isotopic age is well correlated with iron oxidation, and consistent with K-Ar age. Octahedral and interlayer cations including Rb and Sr were partly released from the oxidizing biotite by excess positive charge from iron oxidation. Divalent /sup 87/Sr decayed from monovalent /sup 87/Rb was more easily released from biotite, resulting in the reduction of Rb-Sr isotopic age. Weathered biotite is not suitable for the age dating of parent rocks, but behaviour of radiogenic isotopes provides useful information on the geochemical and structural changes of biotite during weathering.

• Membrane and Water Treatment
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• v.9 no.2
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• pp.69-77
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• 2018

The use of membrane as an innovative technology for water treatment process has now widely been accepted and adopted to replace the conventional water treatment process in increasing fresh water production for various domestic and industrial purposes. In this study, ultrafiltration (UF) membranes with different formulation were fabricated via phase inversion method. The membranes were fabricated by varying the polymer concentration (16 wt%, 18 wt%, 20 wt%, and 21 wt%). A series of tests, such as field emission scanning electron microscope (FESEM), pore size and porosity, contact angle, and zeta potential were performed to characterize the membranes. The membrane performance in terms of permeation flux and rejection were evaluated using a laboratory bench-scale test unit with mine water, lake water and tube well as model feed solution. Long hour filtration study of the membranes provides the information on its fouling property. Few pore blocking mechanism models were proposed to examine the behaviour of flux reduction and to estimate the fouling parameters based on different degree of fouling. 21 wt% PVDF membrane with smaller membrane pore size showed an excellent performance for surface water treatment in which the treated water complied with NWQS class II standard.

• Journal of Convergence for Information Technology
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• v.9 no.10
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• pp.254-263
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• 2019

This study was designed to understand the Education recognition, satisfaction, and job preferences of college students majoring in beauty through the DISC behavior type, and to be used as customized career and beauty education data considering individual tendencies through the DISC behaviour type. From September 20 to October 11, 2017, the final questionnaire was analyzed for students of beauty education who lived in South Chungnam Province and Gyeonggi Province. Significant differences in the Education recognition and job preferences of the study participants were shown, followed by D, I, S, and C, and were found to be satisfactory for their majors. Through this study, it is believed that it will be possible to identify the Education recognition, satisfaction and job preferences of college students in beauty education and use them as basic data that can help them decide their career path after beauty education.

• Journal of Apiculture
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• v.34 no.2
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• pp.107-115
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• 2019

Bumblebees have apposition compound eyes (one on either side of the head) of about 6,000 ommatidia and three small single-lens ocelli on the frons of their head capsule. The surface of the eye is smooth and interommatidial hairs, as in the honeybee, are not developed. Each ommatidium (approx. 26 ㎛ in diameter) is capped by a hexagonal facet and contains in its centre a 3 ㎛ wide, columnar light-perceiving structure known as the rhabdom. Rhabdoms consist of thousands of regularly aligned, fingerlike microvilli, which in their membranes contain the photopigment molecules. Axons from each ommatidium transmit the information of their photic environment to the visual centres of the brain, where behavioural reactions may be initiated. Since bumblebee eyes possess three classes of spectrally different sensitivity peaks in a ratio of 1:1:6 (UV= 353 nm, blue= 430 nm and green=548 nm) per ommatidium, they use colour vision to find and select flower types that yield pollen and nectar. Ommatidial acceptance angles of at least 3° are used by the bumblebees to discriminate between different flower shapes and sizes, but their ability to detect polarized light appears to be used only for navigational purposes. A flicker fusion frequency of around 110Hz helps the fast flying bumblebee to avoid obstacles. The small ocelli are strongly sensitive to ultraviolet radiation and green wavelengths and appear to act as sensors for light levels akin to a photometer. Unlike the bumblebee's compound eyes, the ocelli would, however, be incapable of forming a useful image.

• Steel and Composite Structures
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• v.39 no.4
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• pp.401-417
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• 2021

This study experimentally reveals the influence of welding on grade S690Q high strength steel (HSS) butt joints from both micro and macro levels. Total eight butt joints, taking plate thickness and welding heat input as principal factors, were welded by shielded metal arc welding. In micro level, the microstructure transformations of the coarse grain heat affected zone (CGHAZ), the fine grain heat affected zone (FGHAZ) and the tempering zone occurred during welding were observed under light optical microscopy, and the corresponding mechanical performance of those areas were explored by micro-hardness tests. In macro level, standard tensile tests were conducted to investigate the impacts of welding on tensile behaviour of S690Q HSS butt joints. The test results showed that the main microstructure of S690Q HSS before welding was tempered martensite. After welding, the original microstructure was transformed to granular bainite in the CGHAZ, and to ferrite and cementite in the FGHAZ. For the tempering zone, some temper martensite decomposed to ferrite. The performed micro-hardness tests revealed that an obvious "soft layer" occurred in HAZ, and the HAZ size increased as the heat input increased. However, under the same level of heat input, the HAZ size decreased as the plate thickness increased. Subsequent coupon tensile tests found that all joints eventually failed within the HAZ with reduced tensile strength when compared with the base material. Similar to the size of the HAZ, the reduction of tensile strength increased as the welding heat input increased but decreased as the thickness of the plate increased.