• Journal of applied mathematics & informatics
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• 제5권2호
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• pp.553-564
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• 1998

In this paper we introduce a new concept of more weakly quadrant dependence of hitting times of stochastic processes. This concept is weaker than the more positively quadrant dependence of hitting times of stochastic processes. This concept is weaker than the more positively quadrant dependence and it is closed under some statistical operations of weakly positive quadrant dependence(WPQD) ordering.

• Journal of Electrical Engineering and Technology
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• 제12권1호
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• pp.262-271
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• 2017

This paper presents a novel concept of phase swapping to associate multiple flux weakening ranges to a non-salient PM machine without altering any hardware of the machine. The proposed concept enables a dual three-phase machine to be operated with different displacement angles between the two three-phase windings. Hence, different flux weakening ranges using winding switching can be accomplished by applying this concept. It was also demonstrated that the proposed concept can be utilized for the discrete step as well as continuous operation of the machines. Any application requiring a wide speed range operation of up to thirteen times the base speed can benefit from this proposed concept. Analytical, simulation, and experimental results are provided to validate the effectiveness of the proposed concept.

• 대한수학교육학회지:학교수학
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• 제1권1호
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• pp.19-37
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• 1999

In this study, we examined some matters related to the learning of variable concept in school mathematics on the basis of the theoretical foundation from the previous studies(e.g. Davis, 1975; Rosnick, 1981; IK chemann, 1981; Wagner, 1983.) and practices on variable concept teaching by evaluating the current state of that. Matters be discussed are as follows; the use of symbol for place holders in elementary mathematics, the dealing with sets those elements are literals and operations of such sets, the teaching of dummy variable, the construction of literal expressions that contains variables, the labeling indeterminates as a constant, the change in the exact meaning of variable according to the function concept, the teaching of a generalization by means of variables. After considering on these matters that are connected with the teaching-learning of variable concept, we suggested the alternative proposal to the current state of variable concept teaching.

• Advances in Energy Research
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• 제7권2호
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• pp.147-166
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• 2020

Industrial cooling towers are often ageing infrastructure that is expensive to maintain and operate. A novel approach is introduced in which a heat pump circuit is incorporated to reduce the load upon the towers by extracting low-grade energy from the stream sent to the towers and repurposing in on-site processing operations. To demonstrate the concept, a model was constructed, which uses industrial data on cooling towers linked to a smelter's sulphuric acid plant, to allow direct economic and environmental impact comparison between different heat recovery and repurposing scenarios. The model's results showed that implementing a heat pump system would significantly decrease annual operating costs and achieve a payback period of 3 years. In addition, overall CO₂ emissions could be reduced by 42% (430,000 kg/year) and a 5% heat load reduction on the cooling towers achieved. The concept is significant as the outcomes introduce a new way for energy intensive industrial sectors, such as mineral processing, to reduce energy consumption and improve long-term sustainable performance.

• 한국국방경영분석학회지
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• 제8권1호
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• pp.53-70
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• 1982

This thesis develops a more realistic and applicable new set covering model that is adjusted and supplied by the existing set covering models, and induces an algorithm for solving the new set covering model, and applies the new model and the algorithm to an actual set covering problems. The new set covering model introduces a probabilistic covering aistance ($0{\eqslantless}p{\eqslantless}1$)or time($0{\eqslantless}p{\eqslantless}1$) instead of a deterministic covering distance(0 or 1) or time (0 or 1) of the existing set covering model. The existing set covering model has not considered the merit of the overcover of customers. But this new set covering model leads a concept of this overcover to a concept of the parallel system reliability. The algorithm has been programmed on the UNIVAC 9030 for solving large-scale covering problems. An application of the new set covering model is presented in order to determine the locations of the air surveillance radars as a set covering problem for a case-study.

• 한국경영과학회지
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• 제3권2호
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• pp.47-74
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• 1978

This paper reviews the zero-base budgeting whose concept was developed in the late 1960's, and applied to the actual budgeting situations in the early 1970's. Since then, it has been expanded to become one of major tools in corporate planning and control system. The primary purpose of this review is to clarify the followings: 1) concept of zero-base budgeting and its history, 2) relationships among zero-base budgeting, planning and program evaluation, 3) comparison of zero-base budgeting with other budgeting techniques, and 4) implementation procedure. Some discussions are also provided with respect to the practical implications of zero-base budgeting, its advantages and disadvantages, and others. Finally, the possibility of actual application in a local setting is investigated.

• 한국경영과학회:학술대회논문집
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• 한국경영과학회/대한산업공학회 2005년도 춘계공동학술대회 발표논문
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• pp.947-951
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• 2005

The concept of group technology has been successfully applied to many production systems including flexible manufacturing systems. In this paper we apply group technology principles to the economic lot scheduling problem which has been intensively studied over 40 years. We obtain a production schedule of several family products on a single facility where setup times and costs can be reduced by using the concept of group technology. We develop a heuristic algorithm and a hybrid genetic algorithm for the group technology economic lot scheduling problem (GT-ELSP). Numerical example shows that the developed heuristic and the hybrid genetic algorithm outperform the existing heuristics.

• 한국경영과학회:학술대회논문집
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• 한국경영과학회 1993년도 추계학술대회발표논문집; 서강대학교, 서울; 25 Sep. 1993
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• pp.175-184
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• 1993

Modeling the production process is a necessary and essential aspect of the production planning. This paper introduces a theoretical model of the multi-stage production process. A multi-stage production process is regarded as a network of interrelated production activities which use system exogenous inputs of goods in production and the intermediate products transfers between activities to produce final products. Our model is characterized by (1) a few of the production-related assumptions and (2) two types of elements "goods and activities" that are represented in terms of the network terminology. This model is different from the another multi-stage production models, so-called production network models in relation to the production-theoretical concept. It is not based on the concept of the production correspondence and the activity production functions, but the technology model of Koopmans. Koopmans.

• 한국경영과학회:학술대회논문집
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• 한국경영과학회 2001년도 추계학술대회 논문집
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• pp.257-260
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• 2001

The primary objective of Supply Chain Management (SCM) is to optimize the cash, material and information flow considering all components of Supply Chain (SC) . The plan, established for achieving such objective, is called Supply Chain Planning (SCP) . This SCP gives each SC component specific volume or operation task, should be done in specific due date, for optimizing SC. In detail, the degree of accomplishment for SCP, depends on the SCP achievement of each SC components, is very close to successful SCM. However, this achievement is affected by uncertainties about time and volume. In general, reliability concepts means the probability that a product or system will perform its specified function under prescribed conditions without failure for a specified period of time. Therefore, the concept of Supply Chain Reliability (SCR) and an analytic methodology to calculate the degree of achievement SCP using reliability concept are proposed in this paper. SCR means that the degree of achievement for SCP considering all SC components in due date. SCR can be used to measure the performance of whole supply chain and indicate the direction of SCP.

• 한국경영과학회:학술대회논문집
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• 한국경영과학회 2001년도 추계학술대회 논문집
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• pp.128-131
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• 2001

With the advent of the Internet, data centric computing applications, and e-business applications, virtually all network-stored data has become mission critical in nature. This increasing reliance on the access to enterprise data is challenging the limitations of traditional server-storage solutions. As a result, the ongoing need to add more storage, serve more users and back up more data has given rise to the concept of a SAN(Storage Area Network), “a network whose primary purpose is the transfer of data between computer systems and storage elements and among storage elements.” The purpose of this article is to help the managers and researchers make the understanding of a SAN as the possibility of new data repository in e-business era. This paper provides a thorough literature review on this new concept including its structure, its benefits and disadvantages, and its underlying issues.