• Journal of Mechanical Science and Technology
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• 제20권11호
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• pp.1920-1933
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• 2006

Piezoelectric materials produce an electric field by deformation, and deform when subjected to an electric field. The coupling nature of piezoelectric materials has acquired wide applications in electric-mechanical and electric devices, including electric-mechanical actuators, sensors and structures. In this paper, a hollow sphere composed of a radially polarized spherically anisotropic piezoelectric material, e.g., PZT_5 or (Pb) (CoW) $TiO_3$ under internal or external uniform pressure and a constant potential difference between its inner and outer surfaces or combination of these loadings has been studied. Electrodes attached to the inner and outer surfaces of the sphere induce the potential difference. The governing equilibrium equations in radially polarized form are shown to reduce to a coupled system of second-order ordinary differential equations for the radial displacement and electric potential field. These differential equations are solved analytically for seven different sets of boundary conditions. The stress and the electric potential distributions in the sphere are discussed in detail for two piezoceramics, namely PZT _5 and (Pb) (CoW) $TiO_3$. It is shown that the hoop stresses in hollow sphere composed of these materials can be made virtually uniform across the thickness of the sphere by applying an appropriate set of boundary conditions.

• 전자공학회논문지
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• 제51권9호
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• pp.190-199
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• 2014

본 논문에서는 섬모 번들 특성 모델과 통합 전정 유모세포 모델을 제안한다. 기존 전정기관 모델에 관한 연구는 외력이 없는 상태에서 전정 유모세포의 섬모 번들이 가지는 특성이나 시냅스에서 발생하는 활동전위만을 대상으로 진행되었으며 섬모번들의 고유 특성을 고려한 전정신경의 활동전위에 대한 연구는 이루어지지 않았다. 제안된 통합 전정 유모세포 모델은 외력을 반영하였고 서로 다른 규칙성을 가진 유모세포에 대해 각각의 섬모번들의 반강성 특성을 고려하였고 이를 기존의 외력없는 모델과 비교하였다. 그 결과 외부 자극의 변화에 따른 주파수 변화가 큰 불규칙적 신경섬유와 중간규칙적 신경섬유에서는 반강성 구간의 감소를 보였으나 그렇지 않은 규칙적 신경섬유에서는 기존의 반강성 특성과 유사한 특성을 보여주었다. 또한 제안된 전정 유모세포 모델을 통해 11개의 주파수 대역에서의 모델링 데이터와 기존의 동물 실험 데이터가 거의 일치함을 보여 주었다. 제안된 섬모 번들 특성 모델이 적절히 모델링되었음이 확인된다.

• 한국의류산업학회지
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• 제11권5호
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• pp.808-817
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• 2009

The purpose of this study was to verify potential differences in group- specific external feature concerns and beauty care behaviors of Korean women in their 20's~40's depending on their narcissistic propensity. This study is to take psychological approaches to narcissistic propensity of our contemporary society, so that it can get better understanding about consumers and provide marketing data on beauty-related industry. To meet the above goals, total 400 sheets of questionnaire were distributed to subjects from March 30 to April 8, 2009. Out of 376 sheets of questionnaire collected, total 355 valid questionnaires except incomplete 21 ones were used for final data analysis. For data analysis, this study used SPSS 12.0 as statistic program to perform factor analysis, reliability test (Cronbac's ${\alpha}$ coefficient), cluster analysis, t-test, analysis of variance (ANOVA), Duncan's multiple range test and multiple regression analysis. As a result, this study could come to the following findings: First, according to cluster analysis depending upon different factors such as self-directed narcissism, others-conscious narcissism and others-sensitive narcissism, it was found that our women in 20's to 40's could fall into 4 groups, i.e. complex narcissism group, mixed narcissism group, others-sensitive narcissism group and dispirited narcissism group. Second, according to analysis on potential differences in external feature concerns among four groups depending on their narcissistic propensity, it was found that there were significant differences in all relevant factors among groups. Third, according to analysis on differences in beauty care behaviors among four groups depending upon their narcissistic propensity, it was found that there were significant differences in all relevant factors among groups. Fourth, according to analysis on potential factors of external feature concerns that may influence beauty care behaviors of complex narcissism group, it was found that those factors had significant effects on fashion-orientedness, cosmetic surgery and personality pursuit of this group. And it was also found that there were significant differences in fashion-orientedness, cosmetic surgery, makeup and hair styling of mixed narcissism group, others-sensitive narcissism group and dispirited narcissism group respectively.

• 마케팅과학연구
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• 제18권4호
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• pp.277-306
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• 2008

Knowledge1 is considered to be a key element of understanding how organizations gain and sustain competitive advantages. But very few firms are capable of creating the requisite knowledge and thus, firms should acquire and exploit new knowledge through knowledge transfer processes. The empirical part of this study involves examining relationships among adaptability of knowledge and knowledge transfer and marketing performance and testing the moderating roles of absorptive capacity, socialization and local marketing knowledge. This study is organized as follows: (1) Previous literature on knowledge, knowledge transfer and absorptive capacity is summarized, followed by the development of hypotheses derived from the knowledge-based view and absorptive capacity. (2) The hypotheses are tested with data collected from MNCs' subsidiaries performing marketing activities in Korea.Thestudyisclosedwithfindings,implications,andconclusions. Following six research hypotheses are drawn from literature review in related areas: H1: Adaptability of knowledge transferred from the MNCs' headquarters and other subsidiaries is positively associated with knowledge inflows into the receiving subsidiary. H2: The level of marketing knowledge transferred from the MNCs' headquarters and other subsidiaries is positively associated with marketing performance of the receiving subsidiary. H3: Increases in potential absorptive capacity will enhance the relationship between adaptability of knowledge and the level of marketing knowledge transfer. H4: Increases in realized absorptive capacity will enhance the relationship between the level of knowledge transfer and marketing performance of the receiving subsidiary. H5: Increases in socialization activity among the headquarters and subsidiaries will enhance the relationship between adaptability of knowledge and the level of marketing knowledge transfer. H6: Increases in the level of locally developed marketing knowledge will enhance the relationship between the level of knowledge transfer and marketing performance of the receiving subsidiary. The research framework that illustrates the proposed hypotheses is presented in figure 1. The unit of analysis for this study is knowledge transfer from the MNCs' headquarters and other subsidiaries to their subsidiaries operating in South Korea. The population for this study consists of subsidiaries established either as joint ventures or as wholly-owned subsidiaries. A group of 603 foreign firms were drawn from diverse industry organizations and business societies. After personal contact, telephone, fax, and e-mail to request that the respondents complete the questionnaire, 282 valid questionnaires from 133 initial sample companies were collected. The results of the empirical analyses significantly support all of the proposed hypotheses except hypothesis 3. Adaptability of external knowledge promotes knowledge transfer and the relationship is moderated by a firm's potential knowledge absorptive capacity. On the other hand, knowledge transfer improves a firm's marketing performance and a firm's realized knowledge absorptive capacity and local marketing knowledge moderate the relationship. The theoretical and practical implications of the findings in this study are as follows: (1) firms must take seeking, transferring, sharing and exploiting of external knowledge into serious consideration, while simultaneously creating knowledge to support the necessary business operations, remain competitive, and achieve superior performance. (2) Firms should continuously seek to develop their knowledge absorptive capacity (both potential and realized capacity) to absorb, learn and utilize valuable external knowledge. (3) Firms should emphasize not only absorptive capacity, but also development of local knowledge. Firms with strong absorptive capability and local knowledge can learn and transfer more external knowledge, which can be translated into greater levels of competence and performance.

• 전기학회논문지
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• 제63권4호
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• pp.589-595
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• 2014

The error of instrument transformers is measured by connecting the external burden with the secondary terminal of the instrument transformers. Because the error of transformer is affected by the apparent power and power factor of the external burden, an accurate measurement of burden is important for transformer evaluation. We have developed the burden evaluation equipment for both potential transformer and current transformer by employing the series resistor in the range of $20m{\Omega}{\sim}5{\Omega}$ and the parallel resistor in the range of $1M{\Omega}{\sim}500{\Omega}$, respectively, together with visual basic program. We could reduce testing time more than 5 times by employing method developed in this study, compared with that developed in past. This method shows more better reliability by analyzing the evaluation results and fitting graphs of burden measurements. The test results of the developed system is compared with those obtained in the power meter analyzer to verify the validity.

• Journal of Magnetics
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• 제19권4호
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• pp.345-348
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• 2014

Magnetorheological suspensions (MRSs) are smart materials that have the potential to revolutionize several industrial sectors because of their special rheological behaviors. In this paper, MRS, based on carbonyl iron (CI) microparticles that were dispersed in silicone oil with oleic acid, were prepared. We showed that the electroconductibility of MRS was significantly influenced by the intensity of the external magnetic field that was applied. The resistance value can vary from infinite to below $300{\Omega}$ after applying an external magnetic field. The results indicated that this MRS had the property of magnetic-field-tuned insulator to conductor transition. This system has potential applications in controllable MRS electrical devices.

• 대한화학회지
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• 제7권4호
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• pp.264-270
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• 1963

前報에서 誘導한 置換基效果 一般關係式은 溶媒組成에 따르는 常數, Y를 potential energy 項에 代置함으로서 solvolysis 反應에 適用할 수가 있다. 新方程式, $\Delta{\Delta}H^\neq=a'Y+b\Delta{\Delta}S^\neq$, 의 適用性은 文獻에 報告된 35個反應에 對한 直線關係를 調査해 봄으로서 檢討하였다. 結果로 平均 相關係數 0.977을 얻었고, 따라서 이 方程式이 solvolysis反應에 一般的으로 適用됨을 밝혔고, 또 Grunwald-Winstein의 式이 지니는 몇몇 難點을 解決할 수가 있음을 알 수 있었다. enthalypy-entopy 直線效果는 外部 enthalpy와 外部 entropy에 限한 것이며, 嚴格히 말해서 外部 enthalpy entropy 直線效果임을 强調하였다.

• 경영과학
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• 제26권3호
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• pp.205-221
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• 2009

Countries around the world are actively investing in development and industrial application of RFID, a new wireless communications technology widely perceived as a next-generation growth engine with the potential for creation of new business value. In this paper, we empirically study factors influencing the acceptance of RFID by stage of introduction, to contribute making policies aimed at stimulating demand for this technology and accelerating its penetration. The process of acceptance of RFID was divided, in this paper, into three stages: perception, adoption and implementation, and influence factors, both Internal and external to an organization, drawn from existing literature, are analyzed. A conceptual model comprising internal influence factors, including technical, organization and economic factors, and external factors related to environment and this model was tested through structural equation analysis. To obtain data for empirical analysis, we surveyed public institutions and general companies that are potential users of RFID. The data thus collected were analyzed to determine factors influencing the acceptance of RFID by stage, and practical implications for the RFID promotion policy at the level of demand creation and industrial application were derived from the results of this analysis.

• 환경위생공학
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• 제16권1호
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• pp.108-116
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• 2001

It is difficult to task to achieve high biological nutrient removal from municipal wastewater because of low organic content. Volatile fatty acids(VFAs) produced from acid fermentation of food wastes can be utilized as external carbon sources for the biological nutrient process. Significant reduction and stabilization of the food wastes can also be obtained from the acid fermentation. The objective of this study is to evaluate characteristics of acid fermentation of the food wastes. Results obtained from the batch experiment of various organic wastes showed that the food wastes had high potential to be used as an external carbon source because of the largest production of the VFAs with low nitrogen and phosphorus content. The fish waste was found to be the next possible organic waste, while the others such as radish cabbage and molasses waste showed high VFAs consumption potential as a results of high nitrogen and phosphorus content. alkaline hydrolysis of the food waste was carried out using NaOH prior to the acid fermentation. As the alkali addition increased, solubilization of the organics as well as TSS reduction increased. However, fraction of soluble COD to total COD became stable after a sharp increase. Alkali addition greater than 0.5g NaOH per g TS resulted in significant increase in pH.

• 전기의세계
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• 제25권1호
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• pp.95-100
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• 1976

The main purpose of this paper is to study on the transient current due to the change of environmental temperature under no external field in the arrangement of M$_{1}$(metal)-P(polyver)-M$_{2}$(metal). The specimer of polymeric insulator sandwiched by two metal electrodes composes a parallel-plate condenser represented by Maxwell-model. The behaviors of short circuit current flowing in M-P-M arrangement are very complex and the analysis of its conduction mechanism appears to be much complicated. In this paper we can suggest that a contact potential difference as an energetic state exists in the thin film specimen both sides of which are contacted by two different metals having different cook functions. Futhermore the contact potential difference appears to be constant through the course of temperature change, however, the dielectric constant and caparitance of the specimen must be temperature dependent. Accordingly the charge difference induced on both sides of electrodes may be a cause for the shory circuited transient current flowing through the external circuit. It is also suggestive that the results of the observation must be considered in cases of insulation design of electrical machines and D.C. cable for high voltage use.