Showing papers by "Seung Hee Lee published in 2007"

Stabilization of the liquid crystal director in the patterned vertical alignment mode through formation of pretilt angle by reactive mesogen

Abstract: In the patterned vertical alignment (PVA) cell in which multidomains are formed from the perfect vertical alignment through an oblique field only, the formation of disclinations between liquid crystal (LC) molecules is inevitable in the presence of an electric field, which lowers transmittance and the response time. In the proposed PVA device, the pretilt angle is formed in four different directions through the polymerization of an UV curable reactive mesogen monomer at the surface. In this way, the reorientation of LC responding to an electric field is well defined, and thus the device shows reduced threshold voltage and much improved response time in all gray scales.

Effects of carbon nanotubes on electro-optical characteristics of liquid crystal cell driven by in-plane field

Abstract: Homogeneously aligned nematic liquid crystal (LC) cells doped with carbon nanotubes (CNTs) driven by an in-plane field were fabricated and their electro-optic characteristics were investigated. The effective cell retardation values showed no difference between doped and undoped LC cells in the absence of electric field. However, in the presence of electric field, it was smaller in the CNT-doped cell than in the undoped cell, resulting in the decrease of transmittance. Furthermore, the CNT-doped cell exhibited a slight increase in the driving voltage due to the increase of the twist elastic constant (K22) and the decrease in the decay response time due to the decrease in the rotational viscosity (γ) and γ∕K22 compared to the undoped cell.

Electroactive superelongation of carbon nanotube aggregates in liquid crystal medium.

Abstract: We report an effect of superelongation of carbon nanotube (CNT) aggregates driven by the electric field in a liquid crystal (LC) medium. The CNT aggregates started to elongate above a certain threshold field and sustained the elongation up to nearly 400% in the linear region with a large electroactive constant of 70 (V/microm)-1. The original morphology of the CNT aggregates was restored upon removal of the field. The elongation was fully reversible below a certain breakdown field, irrespective of the nematic or isotropic phase of the LC medium. The overall process involved (i) the alignment of CNT aggregates to increase the dipole energy of aggregates in the presence of the bias voltage, (ii) stretching of the CNTs by sliding-out from the bundles, and (iii) the entropic elasticity that restores the randomly entangled CNT network of the original aggregates after suppression of the bias voltage.

Recent Trends on Patterned Vertical Alignment (PVA) and Fringe-Field Switching (FFS) Liquid Crystal Displays for Liquid Crystal Television Applications

Abstract: This paper reviews the recent trends on super-patterned vertical alignment (S-PVA) and fringe-field switching (FFS) technologies for liquid crystal display (LCD)-television (TV) applications. For PVA mode, Samsung originally announced S-PVA technology in 2004 to enhance off-axis viewing quality of conventional PVA mode. S-PVA is a new technology which enables screen quality advantages over super-in plane switching (S-IPS) and multi-domain VA (MVA), including high transmittance, >2300:1 contrast ratio, and wide viewing angle with no off-axis image inversion. This paper explores and updates Samsung's latest developments toward its goal of ultimate LCD-TV performance. For FFS mode, the technology appeared in 1998 by HYDIS and now it has been commercialized in all kinds of display applications, implying its technical importance. This paper reviews recent developments and performance of LCD-TV using the FFS mode based on published papers and our knowledge.

Dynamic response of carbon nanotubes dispersed in nematic liquid crystal

Abstract: The alignment and dynamic response of carbon nanotubes (CNTs) in nematic liquid crystal (NLC) medium induced by strong electric field have been observed through polarizing optical microscope. Density-functional calculations suggest that LC molecule anchors helically to the CNT wall to enhance π-stacking with a binding energy of nearly -2.0 eV due to a considerable amount of charge transfer from LC molecule to CNT, resulting in the formation of excess charges and permanent dipole moment in CNTs. Under strong electric field, the motion of CNTs distorted the director of adjacent LC molecules. Our detailed analysis of dynamics revealed that the four-lobe textures in vertical cell and two vertical stripes in in-plane switching cell were strongly correlated, i.e., the side view of textures by the vertical motion of CNTs in vertical cell was similar to the textures in in-plane switching cell. Interestingly, the magnitude of textures in microscope was strongly dependent on the size of CNTs and the applied field strength. The statistical size distribution of textures similar to that of CNTs provided information for the degree of dispersion of CNTs.

Viewing angle switching of vertical alignment liquid crystal displays by controlling birefringence of homogenously aligned liquid crystal layer

Abstract: Viewing angle switching from a wide viewing angle to a narrow viewing angle has been studied Conventional multidomain vertical alignment (VA) mode offers the advantages of a high contrast ratio (CR) not only in the front view but also in the wide viewing directions only if compensation films such as a negative C plate and a positive A plate are used The positive A plate can be replaced by a homogeneous aligned (HA) liquid crystal layer, and the retardation of the HA layer at the off axis can be controlled by applying an electric field while keeping the retardation value at zero in the normal direction Consequently, the viewing angle range of a VA device can be controlled from a wide viewing mode (over 170° in terms of CR=10) to a narrow viewing angle mode (approximately 60° in terms of CR=2) in the horizontal direction while keeping a high image quality at the normal direction

Wide-view transflective liquid crystal display for mobile applications

Abstract: A high optical efficiency and wide-view transflective liquid crystal display based on fringe-field switching structure is proposed. The transmissive part has a homogenous liquid crystal (LC) alignment and is driven by a fringe electric field, which exhibits excellent electro-optic characteristics. The reflective part has a hybrid LC alignment with quarter-wave phase retardation and is also driven by a fringe electric field. Consequently, the transmissive and reflective parts have similar gamma curves.

Dielectrophoresis force driven dynamics of carbon nanotubes in liquid crystal medium

Abstract: This work reports the translation motion of carbon nanotubes (CNTs) dispersed in nematic liquid crystal (NLC) under an ac electric field. This effect was studied for homogeneously and vertically aligned NLC cells driven by in-plane field and vertical electric field, respectively. Long axis of the CNTs is aligned along the liquid crystal director, and above the critical field, the director of the NLC is distorted due to translation motion of CNTs in NLC. The amplitude of this translation motion decreases with increasing frequency, whereas the critical field increases with increasing frequency. We present the mechanism of translation motion of CNTs and model this observed phenomenon based on dielectrophoretic force.

Control of the defect in the liquid crystal director field on the slit of the patterned vertical alignment cell

Abstract: In this letter the authors studied the method to control the position of the generated defect on the slit of the patterned vertical alignment liquid crystal (LC) cell with dynamic stability. The authors modeled the LC director field with a defect on the slit and proposed an advanced wing pattern with a defect trap to stick the defect outside the active area. This shape can prevent the generation of the defect on the slit in the active area even if the authors increase the operation voltage, so that the LC dynamics on the slit is very stable and optical transmittance becomes higher.

A single-gap transflective fringe field switching display using a liquid crystal with positive dielectric anisotropy

Abstract: There is considerable difficulty in fabricating a reflector with embossing in an array substrate using a conventional single gap transflective fringe-field switching nematic liquid-crystal display. In order to solve this problem, we propose a new structure, which consists of a reflector on a colour filter substrate. The newly proposed structure with a complex field direction has problems such that the voltage-dependent transmittance and reflectance curves do not match each other, which necessitate a dual driving circuit. This paper reports the optimized electrode structure and calculated electro-optical results realizing a single gamma curve and high light efficiency.

Unusual double four-lobe textures generated by the motion of carbon nanotubes in a nematic liquid crystal.

Abstract: Unusual double four-lobe nematic liquid crystal (LC) textures were observed in the carbon nanotube (CNT)-doped nematic LC under electric field. Through the electro-optical studies in a wide range of vertical electric fields in the direction of the long axis of the LC molecules, it was realized that the double four-lobe nematic LC textures were formed in the range of 120 to 160 V(rms) at 1 Hz. The formation of these unusual double four-lobe nematic LC textures could originate from the electric field-induced movement of CNTs and the subsequently frustrated reorientation of LCs.

Wideband quarter-wave liquid crystal cell with wide viewing angle for the reflective mode with single polarizer

Abstract: In this letter, the authors propose an optical configuration for the reflective liquid crystal (LC) cell with single polarizer, which can show the wideband property for high contrast in oblique incidence The cell consists of a biaxial, a half-wave retarder, a quarter-wave LC cell, and a positive C plate in addition to a reflector They optimize the configuration of the reflective LC cell on the Poincare sphere using trigonometric calculation In order to verify the optical performance, the authors experimentally compare the optical characteristics of the proposed LC cell with those of the conventional LC cell

Fashion Brand Attachment and Attitudes Toward Brand Extension

Abstract: The purpose of this study was to examine the effects of fashion brand attachment on attitudes toward brand extension. Two hundred thirty-four female college students participated in this study. For this study, Bean Pole brand was selected for the example of brand extension through three pre-test. For data analysis, descriptive statistics, factor analysis, multiple regression, and ANOVA were used for this study. As the results, first, brand attachment was classified into three factors such as `love`, `trust`, and `interest` factors. Second, attitudes toward brand extension were divided into two factors such as similarity of brand extension and purchasing intention. Generally, higher scores on brand attachment was correlated with higher scores on altitudes toward brand extension. Third, results revealed that generally `love` and `trust` factors had affected `attitudes toward brand extension` or `purchasing intention`. Fourth, among the three groups (heavy/middle/low) of brand attachment, the heavy group showed higher preference of brand extension attitudes. Based on these results, fashion brand marketing strategies would be suggested.

A Globalization-Focused Human Resource Development Program in Fashion Marketing Area -Comparison of Korean and U.S. Graduate School's Fashion Marketing Curricula-

Abstract: The purpose of this study was to provide a suggestion for the globalization-focused in fashion marketing area through an analysis of curricula related to fashion marketing of Korean and USA graduate schools. This study analyzed the curricula of 34 Korean graduate schools and 18 USA graduate schools. As a result, it was revealed that the curricula of Korean schools were different from those of USA graduate schools. The average number of the fashion marketing classes of the Korean schools was 10.7, while the average of the USA was 10.4. However, when examined the percentages of fashion marketing classes among total number of classes, the average of Koreans was much lower(16.1%) than Americans(50.3%). It means that the schools of USA has higher percentage of curricula related to fashion marketing than those of Korea. The percentage of USA research method courses was higher than those of Korean. Based on the results, this study suggests that more diverse curricula related to fashion marketing and research methods in Korea need to be developed in order to produce global human resource development in fashion marketing area.

A Fringe-Field Driven Hybrid Aligned Nematic Liquid Crystal Display for Narrow Viewing Angle Display

Abstract: Liquid crystal displays (LCDs) that exhibit a high image quality at the normal direction only were investigated. For this purpose, a hybrid aligned nematic liquid crystal (LC) cell driven by a fringe electric field was chosen, and its electro-optic characteristics with an optimal cell structure were evaluated. The device showed a high light efficiency of 90%, a low driving voltage and a narrow viewing angle < 30° in terms of a CR of 2:1 along the horizontal direction, which is suitable for private display applications.

The Effects of Factors of Fashion-Retail-Entertainment on Store Image & Store Loyalty

Abstract: The purpose of this study was to investigate the relationship among fashion retail-entertainment, store image and store loyalty. Two hundred eleven who female college students living near Seoul area participated in this study. Two hundred sample used for data analysis. For data analysis, frequency, factor analysis, correlation analysis and multiple regression analysis were used. The results were as follows: First, fashion retail-entertainment had 4 factors such as shopping environment, sales service, dining facilities, and others. Store image composed of psychological image, merchandise mix, customer service, and advertising exposure. Store loyalty had 3 factors; cognitive loyalty, intentional loyalty, emotional loyalty. Second, retail-entertainment factors had positive influences on store image and store loyalty. Third, store image had positively affected on store loyalty. Based on these results, successful strategies for fashion retail-entertainment business would provide.

Vascular access apparatus

Abstract: Disclosed is a vascular access apparatus including a needle having an internal lumen to communicate with a blood passage and implanted in the patient's body, a driving part for transporting the needle in a manner such that the needle tip is expelled from the patient's body, and a controlling part for controlling the operation of the driving part in response to a signal. The vascular access apparatus is advantageous in that it is convenient to use because needle insertion and removal motions are automatically performed, repetition of needle piercing is not required because the needle can be precisely inserted into a target position, it is possible to reduce the number of needle piercing motions, thus reducing the number of times that pain is applied to a patient, and it is possible to alleviate the degree of pain applied to a patient because needle piercing is performed without being anticipated by the patient.

Empirical Study on Variables Affecting Consumer Ethics Related to Fashion

Abstract: The purpose of this study was to examine variables affecting fashion consumer ethics. 202 consumers living in Seoul and its suburb participated in this study. Data were analyzed by using descriptive statistics, factor analysis and multiple regression for this study. As the results, consumer ethics was classified into three factors such as `Purposely illegal behavior`, `Tacitly illegal behavior` and `Socialized illegal behavior` factors. Second, regarding ethics judgement, machiavellianism only had affected consumer ethics. Results showed that `Tacitly illegal behavior` and `Socialized illegal behavior` of consumer ethics affected consumer ethics on Fashion Products. Finally, results of multiple regression revealed that psychological factors such as compensatory purchasing, materialism and propensity of religion accounted for 19% of the explained variance in fashion consumer ethics. Based on these results, a fashion educational program about consumer ethics related to fashion industry would be suggested.

Tween Girls and Their Mothers: Clothing Decision Criteria and Body Satisfaction

Abstract: The purpose of the research was to explore clothing characteristics that tween girls(ages 9-14) consider important when deciding what to wear, as well as what the tween girls` mothers believe that their daughters value. The purposive sample consisted of 41 mother-daughter pairs recruited by (Textile/Clothing Technology Corporation). Subjects were divided into younger(9-11) and older(12-14) normal- and plus-size groups based on Body Mass Index(BMI). There were significant differences between mothers and daughters in rating the importance of seven decision criteria concerning what to wear. The entire tween girls reported that clothes that fit well as the most important criteria in deciding what to wear. Clothes that were comfortable was the only criterion significantly related to the tween girls` body dissatisfaction scores. Mothers rated clothes that are the newest fashion and that friends would be wearing as being significantly more important than their daughters reported. There was a significant negative correlation between tween girls` body dissatisfaction scores and choosing clothes that are comfortable. Normal-size tweeen girls and their mothers differed significantly only when considering the newest fashion and what friends would be wearing. Plus-size tween girls and their mothers differed significantly for four criteria: fit, comfort, best looking, and what friends would be wearing. Both younger and older groups differed with mothers concerning what friends would be wearihng. Additionally, younger girls placed significantly more emphasis than their mothers fit. Older girls did not consider the newest fashion an important a decision criterion, but their mothers believed that they did.

The Effects of Fashion Luxury Brand Loyalty on Attitudes toward Counterfeits

Abstract: The purposes of this study were to examine attitudes toward countefeits among fashion luxury brand consumers, and to investigate the influences or effects of brand loyalty on purchasing frequency of fashion luxury brand and the effects of brand loyalty on attitudes toward counterfeits. The subject used for this study were 214 female consumers who have purchased fashion luxury brand products. For data analysis, descriptive statistics, factor analysis, multiple regression, and ANOVA were used. As the results, first, the brand loyalty were classified into three factors; enduring brand loyalty, symbolic brand loyalty and famous brand loyalty. Second, the attitudes toward counterfeit was composed of four factors; comparison with genuine goods, counterfeits as alternative, approval of counterfeits purchase, and illegality of counterfeit manufacturers. Third, purchasing frequency significantly influenced on the attitudes toward counterfeits finally, higher brand loyalty group had more negative attitudes and lower purchasing intention toward counterfeits than other groups. Based on these results, prevention marketing strategies of counterfeit goods would be provided.

Effects of carbon nanotubes on physical properties of nematic liquid crystal and liquid crystal devices

Abstract: Recently, active researches on carbon Nanotube (CNT)-doped liquid crystal (LC) mixtures are progressing. Based on experimental observations, CNTs are known to align parallel to the LC director and experience orientational deformation associated with the LC deformation under an electric field. Theoretical calculation also shows that the LC is strongly anchored on CNT in a way that the LC director is parallel to the CNT long axis. Many experimental results have been reported regarding to CNT effects on electro-optic characteristics of the LC device such as threshold voltage, residual dc and response time, and physical properties of a nematic LC such as rotational viscosity, dielectric anisotropy, elastic constants and clearing temperature, although some are still controversial. In this talk, historical reviews as well as our achievements on CNT-LC mixtures will be discussed.

A Study on the Effect of Attitude toward Fashion Counterfeits on Variables Related to Luxury Brand

Abstract: The purpose of this study was to examine the effect of attitudes toward fashion counterfeits on brand attachment and equity. Four hundred-eight female college students in Seoul and its suburb responded for this study. For data analysis, descriptive statistics, factor analysis, and multiple regression were used for this study. The results of this study were as follows. First, attitude toward fashion counterfeits was classified into three factors such as goodwill, approve of purchase, and counterfeit quality factors. Second, brand attachment was classified into four factors such as love, interest, perception and trust factors. Third, brand equity was classified into five factors such as loyalty, quality, image and recognition factors. Generally, attitudes toward fashion counterfeits factors were correlated with lower scores on brand attachment and brand equity. Finally, the results revealed that attitudes toward fashion counterfeits had a negative effect on brand attachment and equity. Brand attachment had a positive effect on brand equity, and also brand attachment and brand equity had a positive effect on purchasing intention. Based on these results, fashion brand marketing strategies would be suggested.

Analysis of Light Modulation in the Fringe-Field Switching Liquid Crystal Mode

Abstract: The light modulation mechanism in conventional liquid crystal displays (LCDs) presents either phase retardation or polarization rotation effects only. However, in the fringe-field switching (FFS) mode, both effects exist depending on the electrode positions when the electrode width and distance is larger than 2 μm. Interestingly, when the electrode width and distance are reduced to less than 2 μm, only the polarization rotation effect exists. Further, reduction of the electrode width and distance gives rise to improved response time and light efficiency in the FFS mode.

Static Configuration of the Super In-Plane Switching Liquid Crystal Director on the Electrode

Abstract: In this work we investigate dynamic behavior of the LC director including the defect nucleation and the LC director field on the shape of the electrode using the Q-tensor method in the Super IPS cell. In general, the Q-tensor method can model the defect dynamics in a liquid crystal director field in addition to electrical behavior of the LC director.

Factors Affecting Addictive Shopping Behavior on Fashion Product Comparison of Off-line & On-line Shopping

Abstract: The purposes of this study were to investigate factors affecting addictive shopping behavior and to compare the factors affecting between on-line and off-line addictive shopping. Four hundred eighty-nine female college students who have purchased fashion goods on-line shopping or off-line shopping were surveyed. For data analysis, descriptive statistics, Pearson`s correlations, t-test, and multiple regression analysis were used. As the results, 15.5% of respondents were revealed as addictive buyers. Approximately 18% and 13% of subjects were revealed as on-line addictive buyers and off-line addictive buyers. There were statistically significant differences between addictive buyers and non-addictive buyers regarding self-mastery, depression, stress, and impulse. Addictive consumption scores were correlated to lower self-mastery, higher depression, and higher stress. Factors such as self-mastery, stress, impulse showed differences between on-line and off-line addictive buyers. Also, there were statistically significant differences between on-line and off-line addictive buyers. Based on these results, fashion social responsibility marketing strategies and implications regarding on-line and off-line shopping addiction would be suggested.

A Study on CRM in TV Home Shopping (Part 1)

Abstract: The purpose of this study was to examine which variables affect customer relationship management in TV home shopping. Three hundred customers who had purchased fashion products in TV home shopping had participated in this study. The data was analyzed by factor analysis, t-test, correlation analysis and path analysis using SPSS program. As the result, `service`, `information`, `contents`, `reputation`, and `benefits` variables had the effects on `trust`: especially, `service` had the major effects on `trust` The `trust` and `security` had the effects on `commitment`. The `price` variable had only effect on relationship maintenance. Also, `trust` and `commitment` had the `relationship maintenance` Specifically `commitment` had higher effect on relationship maintenance than `trust` did. The results of this study would provide CRM marketing strategy for fashion marketers of TV home shopping.

A Study on Variables Affecting Shoplifting Fashion Items

Abstract: The purposes of this study were to identify shoplifting items and assess consumers` attitudes toward shoplifting, and to determine the variables to effect shoplifting Three hundred ninety-eight respondents of high school students were used for data analysis Descriptive statistics, t-test, and multiple regression analysis were used Results indicated 178% of the respondents experienced fashion item shoplifting in the last 3 years Shoplifting fashion items were categorized accessory, apparel, and cosmetic, and so on Generally fashion item shoplifters demonstrated generous attitudes toward shoplifting than non-shoplifters There were statistically significant differences between shoplifters and non-shoplifters in that shoplifters showed more hedonic shopping orientation and higher compulsive buying than non-shoplifters did Also, fashion item shoplifters were more likely to have high depression and binge eating behavior Shoplifting attitudes were correlated with lower self-esteem and higher depression, hedonic shopping orientation, compulsive buying, and binge eating Results of multiple regression revealed that hedonic shopping orientation and compulsive buying was significantly related to shoplifting attitudes Based on these results, fashion marketing strategies to protect shoplifting would be suggested