• 대한기계학회논문집A
• /
• 제21권10호
• /
• pp.1598-1608
• /
• 1997

Based on the application of te theory of conjugate approximations and the Loubignac's iterative method in a local region, a method to improve the stress filed in a displacement-formulated finite element solution has been proposed. The validity of the proposed method has been tested through two examples : a thick cylinder under internal pressure loading and an infinite plate with a central circular hole subjected to uniaxial tension. As a result of analysis of the examples, it was found that the stress field obtained for the local region model by the proposed method approximates well for the whole domain model. In addition, it was found that because of a significant decrease in the computing time to obtain the improved stress field, the proposed method is efficient and useful for the detailed stress analysis in local regions.

• JSTS:Journal of Semiconductor Technology and Science
• /
• 제7권2호
• /
• pp.120-131
• /
• 2007

A comprehensive short channel analytical model has been proposed for High Electron Mobility Transistor (HEMT) to obtain higher cut-off frequency maintaining the reliability of the device. The model has been proposed to consider generalized doping variation in the directions perpendicular to and along the channel. The effect of field plates and different gate-insulator geometry (T-gate, etc) have been considered by dividing the area between gate and the high band gap semiconductor into different regions along the channel having different insulator and metal combinations of different thicknesses and work function with the possibility that metal is in direct contact with the high band gap semiconductor. The variation obtained by gate-insulator geometry and field plates in the field and channel potential can be produced by varying doping concentration, metal work-function and gate-stack structures along the channel. The results so obtained for normal device structure have been compared with previous proposed model and numerical method (finite difference method) to prove the validity of the model.

• Animal Systematics, Evolution and Diversity
• /
• 제28권4호
• /
• pp.269-278
• /
• 2012

Gobiids are hyperdiverse compared with other teleost groups, with about 2,000 species occurring in marine, freshwater, and blackish habitats, and they show a remarkable variety of morphologies and ecology. Testing the effectiveness of DNA barcodes on species that have emerged as a result of radiation remains a major challenge in evolutionary biology. Here, we used the cytochrome c oxidase subunit 1 (COI) sequences from 144 species of gobies and related species to evaluate the performance of distance-based DNA barcoding and to conduct a phylogenetic analysis. The average intra-genus genetic distance was considerably higher than that obtained in previous studies. Additionally, the interspecific divergence at higher taxonomic levels was not significantly different from that at the intragenus level, suggesting that congeneric gobies possess substantial interspecific sequence divergence in their COI gene. However, levels of intragenus divergence varied greatly among genera, and we do not provide sufficient evidence for using COI for cryptic species delimitation. Significantly more nucleotide changes were observed at the third codon position than that at the first and the second codons, revealing that extensive variation in COI reflects synonymous changes and little protein level variation. Despite clear signatures in several genera, the COI sequences did resolve genealogical relationships in the phylogenetic analysis well. Our results support the validity of COI barcoding for gobiid species identification, but the utilization of more gene regions will assist to offer a more robust gobiid species phylogeny.

• Industrial Engineering and Management Systems
• /
• 제12권3호
• /
• pp.190-197
• /
• 2013

People are living longer than ever before. As a result, life expectancy is going up and the demand of long-term care facilities is increasing in most countries. The facilities provide rehabilitative, restorative, and skilled nursing care to patients or residents in need of assistance with activities of daily living. This study deals with the capacitated location and allocation problem of long-term care facilities in a city that consists of a finite number of regions. Assuming that in each region candidate locations for three types of facilities are already given, two integer programming models are developed under the closest assignment rule reflecting the demand characteristics of the facilities. Both the location and type of the facilities to be built become decision variables. To show the validity of the models, numerical problems are solved with commercial software, CPLEX. Also, sensitivity studies were conducted to identify relationships between the system parameters.

• Journal of Mechanical Science and Technology
• /
• 제18권1호
• /
• pp.82-91
• /
• 2004

This article deals with a minimum energy control law of S-CVT connected to a dc motor. The S-CVT can smoothly transit between the forward, neutral, and reverse states without any brakes or clutches, and its compact and simple design and its relatively simple control make it particularly effective for mechanical systems in which excessively large torques are not required. And such an S-CVT equipped power transmission has the advantage of being able to operate the power sources in their regions of maximum efficiency, thereby improving the energy efficiency of the transmission system. The S-CVT was intended to primarily for use in small power capacity transmissions, thus a dc motor was considered here as the power source. We first review the structure and operating principles of the S-CVT, including experimental results of its performance. And then we describe a minimum energy control law of S-CVT connected to a do motor. To do this, we describe the results of an analysis of the dynamics of an S-CVT equipped power transmission and the power efficiency of a DC motor. The minimum energy control design is carried out via B-spline parameterization. And we show numerical results obtained from simulations illustrate the validity of our minimum energy control design, benchmarked with a computed torque control algorithm for S-CVT.

• 환경영향평가
• /
• 제20권2호
• /
• pp.123-131
• /
• 2011

The objective of this study is to prepare the effective management plan of environmental noise with a noise map, and the guideline on the management plan of environmental noise was suggested through the review of existing application examples. The management plan of environmental noise with a noise map includes the practical contents in the stages of subdivision of management areas, establishment of reduction measures, opinion collection, post investigation, and reformulation of management plan. First, the classification of management regions is performed considering the excess degree of noise standard and the facility type in the phase of subdivision of management areas. Second, the optimal management plan is established through the investigation of regional characteristics and various noise reduction measures in the phase of establishment of reduction measures, which includes the examination of noise reduction effects with a noise map and the budget planning with the costing of noise reduction measures. Third, the opinion survey with a local resident and a expert is carried out in order to prove the validity of the management plan in the phase of opinion collection, and the management plan is modified with gathered opinions. Fourth, the post examination plan with noise measurement is performed in order to verify the real effect of noise reduction measures according to the management plan in the phase of post investigation. Finally, the amendment of the management plan as well as the improvement of a noise map is carried out at a regular cycle in the phase of reformulation of management plan.

• Journal of Power Electronics
• /
• 제15권2호
• /
• pp.544-554
• /
• 2015

This paper presents a steady-state operation analysis of full-bridge series-resonant inverters focusing on the distorted load current due to low-quality-factor resonant circuits in induction heating and other applications. The regions of operation based on the zero-voltage switching (ZVS) and non-zero-voltage switching (NON-ZVS) operations of the asymmetrical voltage-cancellation control technique are identified. The effects of a distorted load current under a wide range of output powers are also analyzed for achieving a precise ZVS operating region. An experimental study is performed with a 1kW prototype. Simulation and experimental studies have confirmed the validity of the proposed method. An efficiency comparison between the variable frequency method and the conventional fixed-frequency method is provided.

• 전기전자학회논문지
• /
• 제23권2호
• /
• pp.622-627
• /
• 2019

본 논문에서는 비대칭 공극을 갖는 단상 영구자석 동기 전동기의 센서리스 운전을 위한 초기 회전자 위치 검출 알고리즘을 제안한다. 일반적인 센서리스 운전 기법 중 역기전력 기반의 센서리스 제어는 영속 및 저속운전에서 역기전력 정보를 추정하기 어렵다. 이를 위해 오픈 루프 기동 기법이 필수적으로 요구되고 일정한 방향으로의 회전을 위해서는 회전자의 초기 위치 검출이 반드시 필요하다. 본 논문에서는 단상 영구자석 동기 전동기의 자기적 특성을 이용하여 고주파 전압 주입 신호에 옵셋 전압을 추가하여 회전자 자극을 검출하는 기법을 제안한다. 다수의 실험 결과를 통하여 제안된 알고리즘의 유효성과 유용성을 검증하였다.

• The Journal of Asian Finance, Economics and Business
• /
• 제9권10호
• /
• pp.147-158
• /
• 2022

This study examines the relationship between employee engagement and goal orientation toward competence. In addition, it also examines the relationship between competence and employee performance in financial institutions in Indonesia. Questionnaires were distributed to several employees who work at financial institutions in Aceh, North Sumatra, and Riau. The basis for selecting the research object was that most financial institutions have similar business products. The similarities are the marketing of home loan ownership products and multipurpose investments. The three study regions are located in western Indonesia's most central provinces and have a significant amount of trade. The sampling technique used was purposive sampling based on specific criteria for the respondents. 275 employees made up the research sample, and partial least squares data analysis methods were applied. In data analysis, initial testing was carried out on the components of the research statement items to see their validity and reliability. The results of this study indicate that employee engagement behavior can improve employee performance, which improves financial institutions' organizational performance. The study's findings offer suggestions for policies and guidelines that will encourage productive work behavior among employees and boost organizational performance. The fact that employees must think and act creatively to develop their competence and become superior employees is another distinctive feature of this research.

• The Journal of Asian Finance, Economics and Business
• /
• 제8권4호
• /
• pp.43-54
• /
• 2021

The study evaluates India's technological advancement, which has created a range of opportunities for consumers to enter into digital payment space. Demonetization in India has forced all consumers and companies to embrace and create cashless digital payment platforms. The cashless economy scenario involves various factors for its adoption such as reach, availability and awareness. This study considers factors responsible for adopting new digital payment technologies in India's different regions across various consumers. The study includes descriptive statistics and variance analysis (ANOVA) to identify elements to achieve maximum satisfaction. The research collects data from 250 respondents living in India, experiencing digital payments and online transactions. The data is collected through a structured questionnaire and critically analyzed using statistical analysis. The data has been analyzed with no sectorial biases and tracked by creating real-time indications. The study uses various hypotheses after taking responses from a sample of respondents. Cronbach's Alpha analysis is also used to determine the validity and reliability of the data. The study illustrates the complete shift of consumer behavior from cash to a cashless economy. A certain number of factors are shown to directly influence the rate of such a shift toward digital transactions in India.