• 한국경영과학회지
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• 제32권1호
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• pp.93-104
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• 2007

We consider a supply chain where products are shipped to warehouse from manufacturing system to customers. Products are supplied from either in-house regular manufacturing or the secondary source such as subcontractor. The inventory in warehouse is controlled by base-stock policy, that is, whenever a demand arrives from customer, an order is released to the manufacturing system. Unsatisfied demand is backlogged. The manufacturing system is modeled as M/M/s+1/c queueing system, and the orders exceeding the given limit care blocked and lost. The steady state distribution of the outstanding orders and the throughput of the manufacturing system are functions of the level of engagement In the secondary source. There is a profit obtained from throughput and cost not only due to the engagement of the secondary source in the manufacturing system but also inventory positions. We want to maximize the total production profit minus the total cost of the production system by simultaneously determining the optimal level of engagement of the secondary source and the optimal base-stock level of the inventory. We develop two algorithms : one without guarantee of the optimal solution but with the small number of computations, the other optimal but with more computations.

• 한국시뮬레이션학회논문지
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• 제12권2호
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• pp.1-11
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• 2003

In this paper, we focus an optimal policy focus optimal class of (s, S) inventory control systems. To this end, we use the perturbation analysis and apply a stochastic optimization algorithm to minimize the average cost over a period. We obtain the gradients of objective function with respect to ordering amount S and reorder point s via a combined perturbation method. This method uses the infinitesimal perturbation analysis and the smoothed perturbation analysis alternatively according to occurrences of ordering event changes. Our simulation results indicate that the optimal estimates of s and S obtained from a stochastic optimization algorithm are quite accurate. We consider that this may be due to the estimated gradients of little noise from the regenerative system simulation, and their effect on search procedure when we apply the stochastic optimization algorithm. The directions for future study stemming from this research pertain to extension to the more general inventory system with regard to demand distribution, backlogging policy, lead time, and review period. Another directions involves the efficiency of stochastic optimization algorithm related to searching procedure for an improving point of (s, S).

• 드라이브 ㆍ 컨트롤
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• 제20권3호
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• pp.1-8
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• 2023

The purpose of this study was to investigate and compare the impact of engine load on the emission characteristics of excavator engines, with the aim of improving the method for calculating the emission inventory of construction machinery. The engine load in excavators is directly correlated with the operational workload, and variations in the load factor (LF) can significantly influence the emission inventory. Thus, on-board diagnostic (OBD) data from an excavator at a construction site were systematically collected to measure engine output and emissions. The results revealed discernible differences in emissions based on engine load, even when the average excavator engine performance remained constant. This highlights the significant influence of the type and characteristics of the work being carried out on emission characteristics. Making realistic adjustments to the LF used in emission calculation formulas emerges as a crucial strategy for environmental improvement. Moreover, the analysis of the effects of engine load on emissions from excavators provides valuable insights for enhancing environmental protection measures.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2021년도 춘계학술대회
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• pp.157-158
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• 2021

공급망의 빅데이터는 주로 네 가지 측면에서 발생된다. 하나는 생산 장비 품질 데이터, 계획된 조달 데이터, 제품 데이터 등과 같은 공급망에서 기업의 제품 가치 이전 과정에서 불가피하게 생성되는 관련 데이터이고, 두 번째는 공급망에 있는 다양한 회사의 ERP 데이터에서 파생된다. 세 번째는 고객의 전자 상거래 데이터이고 마지막은 외부 또는 수동으로 입력한 데이터의 데이터이다. 따라서 본 연구를 통해서 공급망 운영 과정에서 재고를 예측하고 제어하기 위해 타사 데이터 서비스 센터 분석 및 데이터 마이닝. 그것은 여러 측면에서 전체 공급망에 혁신과 관리 기술 및 사고방식의 변화를 가져오고 마침내 전체 공급망의 재고 조정 및 제로 재고 목표를 달성하게 된다.

• Journal of Korean Neurosurgical Society
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• 제53권1호
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• pp.13-18
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• 2013

Objective : There are few published studies which have documented psychopathological abnormalities in patients with of adolescent idiopathic scoliosis (AIS) The aim of this study was to evaluate the psychopathological influence of AIS in Korean 19-year-old males. Methods : The authors compared the Korean military multiphasic personal inventory (KMPI) military profiles of 105 AIS cases (more than 10 degrees of Cobb's angle without surgical treatment) with the KMPI profiles of 108 normal controls. The AIS group was split depending on Cobb's angle to further evaluate this relation by the severity of AIS. Results : A significantly decreased result on the faking-good response scale and an significantly increased result on the faking-bad response were observed in the AIS group compared to the control (p<0.012). The neurosis scale results, including anxiety, depression and somatization symptoms, were significantly increased in the AIS group compared to the control (p<0.010). The severity level of personality disorder and schizophrenia were also significantly increased in the AIS group (p<0.010). Differences in KMPI scale scores were not related to the severity of AIS. Conclusion : Young males with AIS tend to have abnormal results on the multiphasic personal inventory test compared to normal volunteers, suggesting that AIS may be related to psychopathology in the young male group in Korea. Although these psychopathology in AIS were differently observed compared to normal controls, but not interfered with military life. Clinicians are recommended to pay attention the psychopathological traits of patients with AIS.

• 제어로봇시스템학회논문지
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• 제11권11호
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• pp.956-962
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• 2005

This paper presents an integrated analysis of production and financing decisions. We assume that a cash storage unit is installed to manage the cash flows related with production activities such as raw material procurement, process operating setup, Inventory holding cost and finished product sales. Temporarily financial investments are allowed for more profit. The production plant is modeled by the Batch-Storage Network with Recycle Streams in Yi and Reklaitis (2003). The objective function of the optimization is minimizing the opportunity costs of annualized capital investment and cash/material inventory while maximizing stockholder's benefit. No depletion of all the material and cash storage units is major constraints of the optimization. A novel production and inventory analysis formulation, the PSW(Periodic Square Wave) model, provides useful expressions for the upper/lower bounds and average level of the cash and material inventory holdups. The expressions for the Kuhn-Tucker conditions of the optimization problem can be reduced to two subproblems and analytical lot sizing equations under a mild assumption about the cash flow pattern of stockholder's dividend. The first subproblem is a separable concave minimization network flow problem whose solution yields the average material flow rates through the networks. The second subproblem determines the decisions about financial Investment. Finally, production and financial transaction lot sizes and startup times can be determined by analytical expressions as far as the average flow rates are calculated. The optimal production lot and storage sizes considering financial factors are smaller than those without such consideration. An illustrative example is presented to demonstrate the results obtainable using this approach.

• 한국컴퓨터정보학회논문지
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• 제11권2호
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• pp.295-301
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• 2006

분배시스템에서 완제품에 대한 재고통제 운용전략은 기업들에 있어 많은 관심의 대상이 되어 오고 있으며, 스케일메리트(scale merit)기대를 위한 소종대량 취급방식은 고객 요구의 다양화로 더 이상 지속하기 힘들게 되었다. 이러한 환경변화에 대응하기 위하여 많은 기업들은 다양한 제품을 취급하는 추세에 있다. 그러나 기업이 고객 요구다양화에 부응하기에는 많은 비용이 소요된다. 게다가 잔여재고는 진부화 또는 불량재고가 되어 기업에 부담을 가중시킨다. 이러한 비효율적인 문제해결을 위하여 본 연구는 다종소량 취급 방식과 소종소량 취급 방식의 비용비교를 통하여 물류수송비용 및 재고비용 감소의 합리화를 도출 하였다.

• 제어로봇시스템학회논문지
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• 제16권3호
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• pp.305-312
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• 2010

The aim of this study is to find an analytic solution to the problem of determining the optimal capacity of a batch-storage network to meet demand for finished products in a system undergoing joint random variations of operating time and batch material loss. The superstructure of the plant considered here consists of a network of serially and/or parallel interlinked batch processes and storage units. The production processes transform a set of feedstock materials into another set of products with constant conversion factors. The final product demand flow is susceptible to joint random variations in the cycle time and batch size. The production processes have also joint random variations in cycle time and product quantity. The spoiled materials are treated through regeneration or waste disposal processes. The objective function of the optimization is minimizing the total cost, which is composed of setup and inventory holding costs as well as the capital costs of constructing processes and storage units. A novel production and inventory analysis the PSW (Periodic Square Wave) model, provides a judicious graphical method to find the upper and lower bounds of random flows. The advantage of this model is that it provides a set of simple analytic solutions while also maintaining a realistic description of the random material flows between processes and storage units; as a consequence of these analytic solutions, the computation burden is significantly reduced. The proposed method has the potential to rapidly provide very useful data on which to base investment decisions during the early plant design stage. It should be of particular use when these decisions must be made in a highly uncertain business environment.

• 산업경영시스템학회지
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• 제32권4호
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• pp.53-62
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• 2009

Lee[15] examined quantity discount contracts between a manufacturer and a retailer in a stochastic, two-period inventory model where quantity discounts are provided based on the previous order size. During the two periods, the retailer faces stochastic (truncated Poisson distributed) demands and he/she places orders to meet the demands. The manufacturer provides for the retailer a price discount for the second period order if its quantity exceeds the first period order quantity. In this paper we extend the above two-period model to a k-period one (where k < 2) and propose a stochastic nonlinear mixed binary integer program for it. In order to make the program tractable, the nonlinear term involving the sum of truncated Poisson cumulative probability function values over a certain range of demand is approximated by an i-interval piecewise linear function. With the value of i selected and fixed, the piecewise linear function is determined using an evolutionary algorithm where its fitness to the original nonlinear term is maximized. The resulting piecewise linear mixed binary integer program is then transformed to a mixed binary integer linear program. With the k-period model developed, we suggest a solution procedure of receding horizon control style to solve n-period (n < k) order decision problems. We implement Lee's two-period model and the proposed k-period model for the use in receding horizon control style to solve n-period order decision problems, and compare between the two models in terms of the pattern of order quantities and the total profits. Our computational study shows that the proposed model is superior to the two-period model with respect to the total profits, and that order quantities from the proposed model have higher fluctuations over periods.

• 품질경영학회지
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• 제11권1호
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• pp.2-9
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• 1983

For the optimal achievement of system goals through a systematic analysis of the complex problems, systems engineering provides us the concepts and methodology that include comprehensive interpretability (or understandability), universal applicability, and feasibility. Under this aspect, the main objective of this study is that it introduces mathematical system theory (MST) as the fundamental tool of SE into the Inventory Control among the related parts with IE, and review it's applicability. Through its work, we can find that it has the alternative aspects with which it can replace other existing methods for problem-solving in understanding and analyzing structurally systems in themselves as well as being considerable of the time evolutionary process of a given system.