• Proceedings of the Korean Magnestics Society Conference
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• 2003.12a
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• pp.233-233
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• 2003

• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.1
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• pp.61-65
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• 2010

A commercially available soft PZT wafer that is poled in thickness direction is subjected to longitudinal tensile stress loading in both short and open-circuit conditions. Variations of electric displacement in thickness direction and in-plane strains are measured over time during the loading. Different material responses in the two electrical boundary conditions are explained by the effects of piezoelectrically produced internal electric field on linear material moduli and domain switching mechanisms. Finally, a free energy model of normal distribution is introduced to explain the observed creep behavior, and its predictions are compared with experimental observations.

• Journal of the Korean Society of Clothing and Textiles
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• v.23 no.8
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• pp.1086-1097
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• 1999

본 연구는 청바지 제품 소비자가 쇼핑시 제품이 품절된 상황에 접했을 때 보여주는 상표 전환행동에 관한 것이다. 의류 매장 관리자의 적시 적량의 제품 입고 관리 능력이 부족할 때 발생하게 될 손실을 유추해 보고 어떤 유형의 소비자가 상표 전환을 쉽게 일으키느니를 규명하는 것은 더욱 효과적인 매장 운영 소비자 만족과 고객 관리를 위해 의미있는 일일 것이다. 본 연구는 다음과 같은 목적을 가진다. 1) 제품 품절시 소비자들은 어떤 상표전환 행동을 보이는지 밝힌다. 2) 제품 품절시 대체 상표제품을 구매할 경우 대체 상표 제품의 가격의 영향력이 상표전환 행동과 어떤 관련을 보이는지 밝힌다. 3) 소비자의 쇼핑지향성, 상표충성, 애고 행동, 인구통제적 특성(성별)이 상표전환 행동에 미치는 영향력을 밝힌다. 이러한 목적을 위해 본 연구는 1997년 3월 버지니아주 블랙스버그에 소재한 버지니아 주립대학교 110명의 학생들을 대상으로 설문조사를 이용한 양적연구를 실시하였다 남녀학생 모두가 소비자로서의 역할을 담당할 수 있는 청바지를 선택하여 상표전환 행동에 대한 설문에 답하게 한후 t-test 와 카이 분석을 실시하였다 그결과 20%의 응답자가 품절기 상표전환 행동을 보이는 것을 나타났다 쇼핑시간과 편의성을 덜 중요하게 여기거나 강한 상표 충성을 보이고 의류전문매장이나 백화점을 주로 이용하는 여성 소비자들의 경우 상표전환을 쉽게하지 않는 것으로 나타났다 연구결과를 바탕으로 의류제조업자 및 소매업자의 제품입고에 과한 제언을 하였다.

• Proceedings of the KSME Conference
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• 2001.06a
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• pp.435-440
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• 2001

Piezoelectric solids such as PZT and PLZT have been widely used as sensors and actuators for various smart systems. One of the problems arising in actuator applications is that a larger actuation force needs to be produced from a small system. This naturally leads to local electric field or stress concentration and thereby resulting in a nonlinear behavior inside the system, Hence, it becomes more important to predict the nonlinear behavior of piezoelectric solids. In this paper we investigate the mechanism of nonlinear behavior in those materials and suggest a constitutive and finite element model. The calculation results obtained from the model seem to be qualitatively consistent with experiments.

• Bulletin of the Korean Chemical Society
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• v.30 no.11
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• pp.2680-2686
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• 2009

The synthesis of a novel superabsorbent hydrogel with natural hybrid backbone via graft copolymerization of acrylamide (AAm) onto kappa-carrageenan (kC, as a polysaccharide) and gelatin (as a protein) under classic thermal conditions is described. The Taguchi method as a strong experimental design tool was used for synthesis optimization. A series of hydrogels were synthesized by proposed conditions of Qualitek-4 Software. Considering the results of 9 trials according to analysis of variance (ANOVA), optimum conditions were proposed. The swelling behavior of optimum hydrogel was measured in various solutions with pH values ranging from 1 to 13. In addition, swelling kinetics, swelling in various organic solvents, various salt solutions and On–Off switching behavior were investigated. The hydrogel formation was confirmed by Fourier transform infrared spectroscopy (FTIR) and thermogravimetrical analysis (TGA). Surface morphology of the synthesized hydrogels was assessed by scanning electron microscope (SEM).

• Coupled systems mechanics
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• v.10 no.6
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• pp.521-544
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• 2021

In this work, we present the development of a 3D lattice-type model at microscale based upon the Voronoi-cell representation of material microstructure. This model can capture the coupling between mechanic and electric fields with non-linear constitutive behavior for both. More precisely, for electric part we consider the ferroelectric constitutive behavior with the possibility of domain switching polarization, which can be handled in the same fashion as deformation theory of plasticity. For mechanics part, we introduce the constitutive model of plasticity with the Armstrong-Frederick kinematic hardening. This model is used to simulate a complete coupling of the chosen electric and mechanics behavior with a multiscale approach implemented within the same computational architecture.

• Culinary science and hospitality research
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• v.15 no.2
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• pp.136-149
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• 2009

The purpose of this paper is to explore the types of failed service and its effect on customer's negative emotions in the restaurant business and their influence on customer's behavior. The study examines the restaurant attributes of failed service in order to determine which variables have the greatest impact on customer's negative emotions and behaviors. To accomplish the purpose of this study, a casual model is developed - which analyzes the main antecedents, moderators and consequences of failed service in the restaurant business. The findings of this study are as follows. 4 types of failed services are found: lack of tangibles, doubt of reliability, unresponsiveness, no expressed empathy. They have an effect on customer's negative emotions(regret and disappointment). And the customer's negative emotions brings out negative behaviors(bad actions, switching brand, protest, negative word of mouth). Customer's regret causes bad actions and switching brand, and customer's disappointment caused switching brand and bad information by word of mouth.

• Knowledge Management Research
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• v.22 no.4
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• pp.41-70
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• 2021

The use of social media has many advantages such as knowledge sharing, social networking, and communicating with other people. However, it has given rise to various side effects including stress, Which is defined as social network stress in this study. This study aims to conceptualize social network stress and investigate its effect on switching behavior in social media. For this purpose, we present a research model that consists of the antecedents and consequences of social network stress and test it empirically using LISREL 8.7 based on the structural equation model. The empirical results showed that knowledge sharing and self-disclosure had positive impact on social network stress, which in turn positively influenced social media switching behaviors. In conclusion, we discussed both theoretical and practical implications of this research and suggested its limitations.

• Korean Journal of Materials Research
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• v.34 no.3
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• pp.152-162
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• 2024

In this study, we introduce a novel TiN/Ag embedded TiO₂/FTO resistive random-access memory (RRAM) device. This distinctive device was fabricated using an environmentally sustainable, solution-based thin film manufacturing process. Utilizing the peroxo titanium complex (PTC) method, we successfully incorporated Ag precursors into the device architecture, markedly enhancing its performance. This innovative approach effectively mitigates the random filament formation typically observed in RRAM devices, and leverages the seed effect to guide filament growth. As a result, the device demonstrates switching behavior at substantially reduced voltage and current levels, heralding a new era of low-power RRAM operation. The changes occurring within the insulator depending on Ag contents were confirmed by X-ray photoelectron spectroscopy (XPS) analysis. Additionally, we confirmed the correlation between Ag and oxygen vacancies (V_o). The current-voltage (I-V) curves obtained suggest that as the Ag content increases there is a change in the operating mechanism, from the space charge limited conduction (SCLC) model to ionic conduction mechanism. We propose a new filament model based on changes in filament configuration and the change in conduction mechanisms. Further, we propose a novel filament model that encapsulates this shift in conduction behavior. This model illustrates how introducing Ag alters the filament configuration within the device, leading to a more efficient and controlled resistive switching process.

• Journal of the Korean Magnetics Society
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• v.11 no.6
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• pp.262-266
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• 2001

The magnetic switching volume is known as an important parameter to understand the magnetization reversal process, thermal stability of the written information and media noise. This parameter is influenced significantly by the microstructure of the magnetic layer as well as underlayer. Therefore, we fabricated CoSm/Cr thin films with varying magnetic layer thickness under constant sputtering by using a dc magnetic sputtering machine. The magnetic layer thickness effect on the magnetic switching volume have been studied by the means of magnetic viscosity and dc demagnetization remanence curve mesurements. From these measurements, we found that the switching volumes increased with increasing the magnetic layer thickness, whereas the coercivity showed different behavior. These may be a result of the increased intergranular coupling and the larger volume fraction of the magnetic layer.