• Progress in Superconductivity and Cryogenics
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• v.16 no.1
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• pp.27-31
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• 2014

2G HTS tapes are widely used for various electric machines. In addition, stacked or parallel connected HTS tapes are essentially used to raise transport current level for large capacity electric machines. Therefore, critical current characteristic of stacked tapes need to be studied. Recently developed 2G HTS tapes are fabricated with various defects doping so that tapes possess pinning center to improve the critical current characteristic. During this process, the critical current is determined minimum value in not perpendicular magnetic field but a specific magnetic field angle according to the reported research. However, the effects of magnetic field angle to critical current of multi-stacked 2G HTS tapes have not been examined. In this paper, field coil which is a race-track coil wound by using an HTS tape with iron-core was fabricated to apply angle adjustable magnetic field to the 2G HTS tape samples. We measured critical current of single and multi-stacked two tapes that have different characteristic depending on various magnetic field angle and magnitude in liquid nitrogen environment. Furthermore, results of single and multi-stacked tapes were compared and analyzed.

• Animal cells and systems
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• v.5 no.4
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• pp.327-331
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• 2001

There is a critical developmental period during which brain sexual differentiation proceeds irreversibly under the influence of gonadal hormone. Recently, kinesin superfamily-associated protein 3 (KAP3) gene expressed during the 'critical period' of rat brain differentiation was identified by us (Choi and Lee, 1999). KAP3 functions as a microtubule-based motor that transports membranous organelles anterogradely in cells, including neurons (Yamazaki et al., 1996). mRNA level of KAP3 gene markedly increased before the initiation of puberty. Neonatal treatment of estrogen clearly inhibited the prepubertal increase in KAP3 mRNA level (Choi and Lee, 1999). In the present study, we aimed to investigate the effects of polychlorinated biphenyls (PCBs), as endocrine disruptors (EDs) on the expression of KAP3 gene during the 'critical period' of rat brain development. In our data, PCBs significantly decreased the expression of KAP3 gene in the fetal (day 17) and the neonatal (day 6 after birth in) male and female rat brains. The body weight and the breeding ability were significantly decreased in the PCBs-exposed rats compared with the control. These results showed that PCBs affect the transcriptional level of brain sexual differentiation related gene, KAP3, in the fetal and the neonatal rat brains. The maternal exposure to the PCBs may lead to toxic response in embryonic brain sexual differentiation and breeding ability after sexual maturation. This study indicates that KAP3 gene may be useful as a gene marker to analyze the molecular mechanism of toxic response in the animal brain development and sexual maturation exposed to PCBs.

• Tuberculosis and Respiratory Diseases
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• v.80 no.2
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• pp.153-158
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• 2017

Background: Recently, increased levels of high-mobility group box 1 protein (HMGB1) have been identified in various inflammatory conditions and infections. However, no studies have evaluated the HMGB1 level in nontuberculous mycobacterial (NTM) lung disease, and compared it to mycobacterial lung disease. Methods: A total of 60 patients newly diagnosed with NTM lung disease, 44 culture-positive pulmonary tuberculosis (TB) patients, and 34 healthy controls, were included in this study. The serum HMGB1 concentrations were quantified using HMGB1 enzyme-linked immunosorbent assay kits. Results: Serum HMGB1 level in patients with pulmonary TB or NTM lung disease, was significantly lower than that of the healthy controls. In addition, the serum HMGB1 level in TB patients was significantly lower than patients with NTM lung disease. However, the levels in NTM patient subgroups did not differ according to the causative species, disease progression, and disease phenotype. Conclusion: Although low levels of serum HMGB1 has the potential to be a marker of mycobacterial lung disease, these levels were unable to differentiate disease progression and disease phenotype in NTM lung diseases.

• Asian Journal of Atmospheric Environment
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• v.12 no.1
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• pp.1-16
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• 2018

Ground-level ozone ($O_3$) can be a menace for vegetation, especially in Asia where $O_3$ levels have been dramatically increased over the past decades. To ensure food security and maintain forest ecosystem services, such as nutrient cycling, carbon sequestration and functional diversity of soil biota, in the over-populated Asia, environmental standards are needed. To set proper standards, dose-response relationships should be established from which critical levels are derived. The predictor of the response in the dose-response relationship is an $O_3$ metric that indicates the dose level to which the plant has been exposed. This study aimed to review the relevant scientific literature and summarize the $O_3$ metrics used worldwide to provide insights for Asia. A variety of $O_3$ metrics have been used, for which we discuss their strengths and weaknesses. The most widely used metrics are based only on $O_3$ levels. Such metrics have been adopted by several regulatory agencies in the global. However, they are biologically irrelevant because they ignore the plant physiological capacity. Adopting AOT40 ($O_3$ mixing ratios Accumulated Over the Threshold of $40nmol\;mol^{-1}$) as the default index for setting critical levels in Asia would be a poor policy with severe consequences at national and Pan-Asian level. Asian studies should focus on flux-based $O_3$ metrics to provide relevant bases for developing proper standards. However, given the technical requirements in calculating flux-based $O_3$ metrics, which can be an important limitation in developing countries, no-threshold cumulative exposure indices like AOT0 should always accompany flux-based indices.

• The Journal of Information Systems
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• v.11 no.1
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• pp.51-74
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• 2002

The purpose of this study is to empirically investigate critical success factors for effective implementation of web-based distance learning system. First of all, four critical success factors are theoretically derived from reviewing previous research. They are: (1) learner-related factor including the variables such as teaming ability, learning attitude, and attending motivation, (2) environmental factor including the variables of physical and mental support for learners, (3) instructional design factor represented by one variable, the degree of appropriateness of learning contents, and (4) the factor concerning the level of self-directed learning readiness embracing the variables such as curiosity for learning, openness towards challenge of learning and affection for learning. Subsequently, the relationships between these four critical success factors and the degree of learning satisfaction are empirically investigated. The data for empirical analysis of the research are collected from 1,020 respondents who have already passed the web-based distance learning courses which have been implemented in Information and Communication Officials Training Institute. Out of 1,020 responded questionnaires, 875 data were available for statistical analyses. The main results of this study are as follows. Firstly, the most important factor for successful implementation of the web-based distance learning system is shown to be the instructional design factor, and in the next place, the self-directed learning readiness factor, the environmental factor and the learner-related one in sequence. Secondly, additional analysis of the variables included in the instructional design factor shows that availability of practical information and knowledge is the most influencing variable, and next, interesting composition of contents, reasonable learning amount, optimal level of instruction, and understandable explanation are significantly important in the descending order. Lastly, among learning motivators, strong intention of acquiring business knowledges and skills is found to be the most important satisfier in the web-based distance learning. The theoretical contribution of this study is to derive a comprehensive model of critical success factors for implementing the web-based distance learning system. And, the practical implication of this study is to propose efficient and effective guidelines for developing and operating the web-based distance learning system in the various kinds of organizations.

• Journal of the Institute of Electronics and Information Engineers
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• v.54 no.3
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• pp.138-144
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• 2017

In this paper, we propose a high frequency boosting circuits compensating for age-related hearing loss. The frequency response of this hearing loss is quite similar to that of a low-pass filter of which the critical frequency get lower with age. Therefore the voltage gain of this compensation circuits increase proportionally to the frequency of signals when the frequency is higher than the critical frequency and the voltage is constant irrespective of the frequency of signals when the frequency is lower than the critical frequency. The proposed circuits consist of a differential circuit and a unity gain amplifier. Because the critical frequency of the proposed circuits is controlled simply in the shape of a volume control lever, the aged people can adjust the high frequency boosting level easily according to one's hearing loss level. The critical frequency is continuously controllable in the whole audible frequency band and the gain of this high frequency boosting circuits is above 80dB at 10kHz.

• Earthquakes and Structures
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• v.10 no.1
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• pp.211-238
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• 2016

The Maximum seismic responses of steel buildings with perimeter moment resisting frames (MRF), modeled as complex MDOF systems, are estimated for several incidence angles of the horizontal components and the critical one is identified. The accuracy of the existing rules to combine the effects of the individual components is also studied. Two and three components are considered. The critical response does not occur for principal components and the corresponding incidence angle varies from one earthquake to another. The critical response can be estimated as 1.40 and 1.10 times that of the principal components, for axial load and interstory shears, respectively. The rules underestimate the axial load but reasonably overestimate the shears. The rules are not always inaccurate in the estimation of the combined response for correlated components. On the other hand, totally uncorrelated (principal) components are not always related to an accurate estimation. The correlation of the individual effects (${\rho}$) may be significant, even for principal components. The rules are not always associated to an inaccurate estimation for large values of ${\rho}$, and small values of ${\rho}$ are not always related to an accurate estimation. Only for perfectly uncorrelated harmonic excitations and elastic analysis of SDOF systems, the individual effects of the components are uncorrelated and the rules accurately estimate the combined response. The degree of correlation of the components, the type of structural system, the response parameter under consideration, the location of the structural member and the level of structural deformation must be considered while estimating the level of underestimation or overestimation.

• Journal of the Korean Society of Food Culture
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• v.23 no.2
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• pp.184-193
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• 2008

The purpose of this study was to determine the detailed customer satisfaction and dissatisfaction factors of family restaurants in Korea, and to then classify the factors into 3 groups, inlcuding core service, quality service, and basic service. ‘Core service’ represents the critical factors that generate both satisfaction and dissatisfaction; ‘quality service’ generates only satisfaction; and ‘basic service’ generates only dissatisfaction. This categorization is based on Herzberg’s motivation-hygiene theory (1976) as well as Cadotte & Turgeon (1988). Based on the characteristics of the three groups, differentiation strategies in managing customer service were suggested to the family restaurant managers. A qualitative research method, termed the critical incident technique (CIT), was used in the study. This method helps researchers find new factors or attributes by grouping key issues from the anecdotes (critical incidents) and then categorizing common factors from the key issues. This research categorized key satisfiers and dissatisfiers into 33 factors, which were from 402 critical incidents described by 261 respondents. Eleven factors (response to service failures, food taste and quality, attention paid to customers, coupon/mileage point/discount card, customer’s ordinary requests, waiting, food diversity, food price, facility sanitation, checking out, customer’s special requests) were classified into core service, which required maximum management not regarding the level of customer satisfaction. Six factors (employee attitude, event, education and explanation, complementary food, customer’s mistakes, attention paid to children) were classified into quality service, which required differentiation strategy management. Finally, nine factors (speed of food service, employee’s mistakes, food sanitation, atmosphere and interior, seating, forcing orders, parking, other customers, reservations) were classified into basic service, which required minimum management at the level of the industry standards.

• Journal of Korean Society for Quality Management
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• v.32 no.3
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• pp.216-233
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• 2004

The real estate management includes not only the brokerage, property management, development, investment and consulting which are related to real estate handling, but also the human resources who deal with the real estate business. The level of management quality of Korean real estate business is rather poor. This paper deals with management innovation of real estate management using Six Sigma methodology The main focus of this Paper is to develop strategy Planning, and is to select critical success factors for each strategy to make an advanced management system for real estate business. This paper is a case study, and the target company for this innovation is ERA-Korea Company. Seven strategies are proposed, and for each strategy several critical success factors are suggested. Through this case study, the authors hope that a management quality model for real estate business is proposed, and an improved management method can be adopted in the other real estate companies.

• Journal of the Korean Society of Systems Engineering
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• v.16 no.1
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• pp.84-97
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• 2020

This paper aims to develop an optimized inventory management method for safety critical Instrument and Control (I&C) components. In this regard, the paper focuses on estimating the consumption rate of I&C components using demand forecasting methods. The target component for this paper is the Foxboro SPEC-200 controller. This component was chosen because it has highest consumption rate among the safety critical I&C components in Korean OPR-1000 NPPs. Three analytical methods were chosen in order to develop the demand forecasting methods; Poisson, Generalized Linear Model (GLM) and Bootstrapping. The results show that the GLM gives better accuracy than the other analytical methods. This is because the GLM considers the maintenance level of the component by discriminating between corrective and preventive.