• 복식문화연구
• /
• 제12권4호
• /
• pp.547-565
• /
• 2004

The purpose of this study was to evaluate the level of SCM activities and the logistics performance by SCM of the three company types in fashion industry· fabric suppliers, apparel manufacturers, and retailers. The level of SCM activities was estimated through the examination of seven factors: commitment and leadership of a top management, flexibility of management, understanding of demand characteristics, integrated management organization, information system, cooperative partnership and communication and exchange of opinion. The logistics performance was measured by improvement in customer service(on time delivery ratio of products, returning rate, treat ratio for A/S, order fill rate, substitute providing capability for being out of stock) and delivery cost reduction. Through questionnaire survey, a total of 214 data for 108 companies of three company types were collected: 46 for 40 fabric suppliers, 123 for 64 apparel manufacturers and 45 for 4 retailers. The analysis of SCM activity levels showed that fabric suppliers had higher degrees in the factor of understanding of demand characteristics, and apparel manufacturers had higher degrees in the factor of information systems. For retailers, the factor of communication and exchange of opinion represented higher degrees. The study on relationship between the SCM activity levels and logistics performance showed that the SCM activity factor of understanding of demand characteristics greatly improved a substitute providing capability for being out of stock in fabric suppliers, and information system improved a substitute providing capability for being out of stock, on time delivery ratio of products and order fill rate in apparel manufacturers. In retailers, the SCM activity factor of understanding of demand characteristics decreased returning rate highly and improved on time delivery ratio of products. The study results showed that SCM activities in fashion industry brought more improvement in customer service levels rather than in delivery cost reduction.

• 정보처리학회논문지C
• /
• 제11C권2호
• /
• pp.263-268
• /
• 2004

멀티미디어 응용 서비스에서는 특정 시간 내에 데이터 전송이 이루어져야 하는 시간 의존성이 있다. 이러한 실시간 특성은 네트웍의 QoS 보장을 위한 중요한 요소이다. 네트웍 사용자의 증가와 응용 프로그램의 데이터 전송율의 증가로 네트웍 자원을 효율적으로 사용하기 위한 연구는 계속 진행되고 있다. 종단간(End-to-End) 지연시간 제한 조건을 만족하면서 최소 비용을 갖는(Delay Constrained Least Cost, DCLC) 경로를 찾는 문제는 이미 NP-hard 문제로 알려져 있다. 최소 지연시간 경로의 비용은 최소 비용 경로의 비용보다 상대적으로 높은 경로 비용을 갖으며, 역으로 최소 비용 경로의 지연시간은 최소 지연시간 경로의 지연 시간보다 상대적으로 높은 지연시간을 갖는다. 본 논문에서는 이러한 단점을 극복하여 DCLC문제에 접근하기 위해 링크비용과 지연시간을 확률적으로 조합한 인자를 사용한 새로운 알고리즘을 연구하였다. 최근 Salama에 의해 제안된 DCUR 알고리즘은 최적에 가까운 알고리즘이나, 제안한 알고리즘은 DCUR 알고리즘과 비교하여 종합적인 컴퓨터 시뮬레이션 결과에 의하면 노드 수 200에서 38% 이상의 효과를 보았다. 본 알고리즘의 특징은 선택의 요소로서 새로운 인자를 만들었고, 링크를 순차적으로 선택하지 않고 동적으로 선택하는 방법을 구현하였다는 것이다.

• Journal of Power Electronics
• /
• 제4권1호
• /
• pp.18-27
• /
• 2004

The output storage capacitor of the PFC converters is commonly designed for the selected hold-up time or the allowed output ripple voltage percentage. Nevertheless, this output capacitor is a main contribution factor to the PFC system stability. Moreover, seeking for a minimum output storage capacitor that assures the PFC desired operation under all condition, and providing the advantage of a small size and low cost is the main interesting target for engineering. Therefore, in this issue the design steps of the PFC converter have been discussed depending on three choices, output ripple, hold-up time, and stability. It is cleared that any design must take the minimum required storage capacitor for stability prospective as step-l in deign, then apply for any other specification like hold-up time or ripple percentage.

• 한국항해항만학회:학술대회논문집
• /
• 한국항해항만학회 2017년도 추계학술대회
• /
• pp.27-29
• /
• 2017

Container terminals in Northern Vietnam have recorded an impressive development in recent years. This development, however, also raises a fierce competition among local container terminals to attract customers. Beside the handling charges, the vessels' waiting cost is also an important factor that drive the opinion of users in choosing appropriate terminal. This research plans to estimate the waiting cost in different container terminals in Northern Vietnam by building regression equation that describe the relationship between the rate of throughput/capacity and waiting cost/TEU. Queuing theory with the application of Poisson distibution is used to estimate the waiting time of arrival vessels and uncertainty theory is applied to estimate the vessel's daily expenses. Previous studies suggested two different formation of the equation and according to the research results, cubic equation is more suitable in the given case. The research results are also useful for further research which require calculation of waiting cost per TEU in each container terminal in Northern Vietnam.

• International Journal of Computer Science & Network Security
• /
• 제24권6호
• /
• pp.17-22
• /
• 2024

Software cost and schedule estimation is usually based on the estimated size of the software. Advanced estimation techniques also make use of the diverse factors viz, nature of the project, staff skills available, time constraints, performance constraints, technology required and so on. Usually, estimation is based on an estimation model prepared with the help of experienced project managers. Estimation of software cost is predominantly a crucial activity as it incurs huge economic and strategic investment. However accurate estimation still remains a challenge as the algorithmic models used for Software Project planning and Estimation doesn't address the true dynamic nature of Software Development. This paper presents an efficient approach using the contemporary Constructive Cost Model (COCOMO) augmented with the desirable feature of fuzzy logic to address the uncertainty and flexibility associated with the cost drivers (Effort Multiplier Factor). The approach has been validated and interpreted by project experts and shows convincing results as compared to simple algorithmic models.

• 한국건설관리학회논문집
• /
• 제6권1호
• /
• pp.49-57
• /
• 2005

Construction labor productivity, which is the greatest source of variation in overall construction productivity, is the critical factor for determining the project performance in terms of time and cost, especially during scheduled overtime when extra time and cost are invested. The objective of this research is to select an appropriate type of probability distribution function representing the variability of daily labor productivity during overtime. Based on the results of statistical data analysis of labor performance during different weekly work hours, lognormal distribution is selected in order to take advantage of easiness of generating correlated random numbers. The selected lognormal distribution can be used for development of a simulation model in construction scheduling, cost analysis, and other applications areas where representation of the correlations between variables are essential.

• 한국정밀공학회지
• /
• 제15권5호
• /
• pp.72-84
• /
• 1998

This paper studies the relationship between assemblability and assembly time. After analyzing characteristic factors of bolts and parts, seven different kinds of assemblability parameters were determined according to assembly process, and assemblability was also evaluated. MTM (Method-Time Measurement) and Work factor methods were used for an estimation of assembly time. It shows the relationship can be found on the basis of characteristic factors of parts and bolts by relational graphs and numerical formulas.

• 전력전자학회논문지
• /
• 제24권3호
• /
• pp.207-214
• /
• 2019

In this study, discrete-time domain analysis is proposed to investigate the input current of a buck AC/DC light-emitting diode (LED) driver. The buck power factor correction converter can operate in both discontinuous conduction mode (DCM) and continuous conduction mode (CCM). Two discontinuous and two continuous conduction operating modes are possible depending on which event terminates the conduction of the main switch in a switching cycle. All four operating modes are considered in the discrete-time domain analysis. The peak current-mode control with slope compensation is used to design a low-cost AC/DC LED driver. A slope compensation design of the buck AC/DC LED driver is described on the basis of a discrete-time domain analysis. Experimental results are presented to confirm the usefulness of the proposed analysis.

• Membrane and Water Treatment
• /
• 제8권2호
• /
• pp.137-147
• /
• 2017

A water treatment utility in South Korea operates a large system of pressurized hollow fiber membrane (PHFM) modules. The optimal selection of membrane module for the full scale plant was critical issue and carried out using Risk-based Life Cycle Cost (RbLCC) analysis based on the historical data of operation and maintenance. The RbLCC analysis was used in the process of decision-making for replacing aged modules. The initial purchasing cost and the value at risk during operation were considered together. The failure of modules occurs stochastically depending on the physical deterioration with usage over time. The life span of module was used as a factor for the failure of Poisson's probability model, which was used to obtain the probability of failure during the operation. The RbLCC was calculated by combining the initial cost and the value at risk without its warranty term. Additionally, the properties of membrane were considered to select the optimum product. Results showed that the module's life span in the system was ten years (120 month) with safety factor. The optimum product was selected from six candidates membrane for a full scale water treatment facility. This method could be used to make the optimum and rational decision for the operation of membrane water purification facility.

• 제어로봇시스템학회논문지
• /
• 제13권2호
• /
• pp.154-162
• /
• 2007

In this paper, we propose a new AC-DC converter control method to comply with harmonics regulation(IEC 61000-3) effective for the inverter system of an air conditioner whose power consumption is less than 2,500W. There are many different ways of AC-DC converter control, but this paper focuses on the converter control method that is adopting an input reactor with low cost silicon steel core to strengthen cost competitiveness of the manufacturer. The proposed control method controls input current every half cycle of the line frequency to get unit power factor and at the same time to reduce switching loss of devices and acoustic noise from reactor. This kind of converter is known as a Partial Switching Converter(PSC). In this study, theoretical analysis of the PSC has been performed using Matlab/Simulink while a 16-bit micro-processor based converter has been used to perform the experimental analysis. In the theoretical analysis, electrical circuit models and equations of the PSC are derived and simulated. In the experiments, micro-processor controls input current to keep the power factor above 0.95 by reducing the phase difference between input voltage and current and at the same time to maintain a reference DC-link voltage against voltage drop which depends on DC-link load. Therefore it becomes possible to comply with harmonic regulations while the power factor is maximized by optimizing the time of current flow through the input reactor for every half cycle of line frequency.