• 한국신뢰성학회:학술대회논문집
• /
• 한국신뢰성학회 2005년도 학술발표대회 논문집
• /
• pp.251-257
• /
• 2005

Software system which is essential in operating the computer has gradually become an indispensable element in many aspects of our daily lives and an important factor in numerous systems. In recent years, software cost sometimes exceeds the cost of maintaining the hardware system. In addition to the cost necessary to develop the new software system and to maintain the system, the penalty costs incurred due to software failures are even more significant. In this paper, a cost model incorporating the warranty cost, debugging costto remove each fault detected in the software system, and delivery delay cost is developed. A software reliability model based on non-homogeneous Poisson process(NHPP) is established and the optimal software release policies to minimize the expected total software cost are discussed. Numerical examples are provided to illustrate the results.

• Communications for Statistical Applications and Methods
• /
• 제8권3호
• /
• pp.719-729
• /
• 2001

Overlap Maximization is a sampling technique to reduce survey costs and costs associated with the survey. It was first studied by Keyfitz(1951). Ernst(1998) presented a remarkable procedure for maximizing the overlap when the sampling units can be selected for two identical stratified designs simultaneously, But the approach involves mimicking the behaviour of nonlinear function by linear function and so it is less direct, even though the stratification problem for the overlap corresponds directly to the linear programming problem. furthermore, it uses the controlled selection algorithm that repeatedly needs zero-restricted controlled roundings, which are solutions of capacitated transportation problems. In this paper we suggest a comparatively simple procedure to use linear programming in order to maximize the overlap. We show how this procedure can be implemented practically.

• 시스템엔지니어링학술지
• /
• 제8권2호
• /
• pp.57-67
• /
• 2012

It is the sensitivity and confidentiality of nuclear power plant decommissioning cost that prevent detailed cost information to be released to the public, which causes some limitation to analyze and reuse the costs. This limitation to access cost information means that the lessons learned from preceding cost estimating may not systematically feed back into following cost estimates. As an alternative, decommissioning cost estimation framework is indispensable to reflecting available experience and knowledge for decommission costs. This study provides the cost estimation framework including data flow and structuralization based on engineering and bottom up approach to enhance decommissioning cost estimation.

• 대한안전경영과학회지
• /
• 제10권1호
• /
• pp.145-153
• /
• 2008

The vehicle routing problem determines each vehicle routes to find the transportation costs, subject to meeting the customer demands of all delivery points in geography. Vehicle routing problem is known to be NP-hard, and it needs a lot of computing time to get the optimal solution, so that heuristics are more frequently developed than optimal algorithms. This study aims to develop a heuristic method which combines guided local search with a tabu search in order to minimize the transportation costs for the vehicle routing assignment and uses ILOG programming library to solve. The computational tests were performed using the benchmark problems. And computational experiments on these instances show that the proposed heuristic yields better results than the simple tabu search does.

• Journal of Information Technology Applications and Management
• /
• 제15권3호
• /
• pp.79-90
• /
• 2008

With the corporate environment nowadays being surrounded by plenty of information, the sharing of information among businesses through mutual cooperation tops the list of hot issues. Predictions of demands from the customer, business, or consumer by sharing information can affect the inventory and order production system. However, notwithstanding the importance of sharing information, empirical studies on quantitative use of information still remain insufficient in spite of many a discussion now being made on the sharing of information. This paper proposes to examine the ways meteorological information may affect the rises in the achievements of supply chains in distributive businesses, the kind of information that noticeably affects the consumer behavioral patterns in the distributive businesses but rarely perceived as a form of information shared by businesses. This study is based on a model in which meteorological information has been added as the one used to predict demands, after the beer distribution game has been modified to fit the current status, and simulations under an assumptive situation, where decisions are made on a daily basis, were conducted 50 times for a period of 1000 days for the generalization of the results, while at the same time a Duncan Test was conducted to determine the threshold to use the meteorological information that will be most profitable to the retailer, wholesaler, supplier and the supply chain as a whole. Our findings indicate that corporations have thresholds that vary from business to business depending upon the ratio of backlog costs to inventory costs. At the same time, our findings also show that there existed effective thresholds depending upon the ratio of backlog costs to inventory costs for the performance of the overall supply chain.

• Journal of Korea Trade
• /
• 제24권6호
• /
• pp.115-134
• /
• 2020

Purpose - International trade leads to the international division of labor, improving the efficiency of the global economic system. Transport costs are a more serious barrier to international trade than customs tariffs. An increase in competition in the transport sector may thus lead to a reduction in transport costs. However, if a carrier's nationality significantly influences transport costs, simply adding more competing carriers of different nationalities would be ineffective. Therefore, it is necessary to establish national or regional carriers to influence competition and reduce transport costs. This study investigates this "nationality effect" by treating Hanjin Shipping's collapse as a natural experiment. Design/methodology - The theoretical basis of this study is the 3rd-degree price discrimination in container shipping market. By using the monthly data of container freight rates of Korea, China and Japan, this study shows the so-called Korea Premiums, which are the empirical counterparts of nationality effect in Korea container shipping market. For this empirical investigation, the structural model with state-space form is used and the dummy models are also estimated. In addition, because China has been also affected by the Hanjin's collapse, the China premiums are considered too. Findings - Compared with Japan's case, it is shown that there had been the so-called Korea premiums since the collapse of Hanjin Shipping. These results are robust from both the state-space model and dummy models. The time pattern of Korea premiums was consistent with the market evolution, especially the pattern of substitutability in container shipping markets. In addition, this paper shows the magnitude of Korea premiums. Originality/value - The argument of this study that the nationality effect can be interpreted as an extended concept of the home market effect is original, which is expected to evoke future research efforts. Further, the discussion on the shipping industrial policy from both horizontal and vertical aspects will provide the relevant policy makers with solid information, especially for the policy coordination in a global scale.

• 해양환경안전학회지
• /
• 제16권2호
• /
• pp.229-234
• /
• 2010

최근 온실가스 감축을 위한 세계 각국의 노력이 다각도로 진행되고 있으며, 국제적인 협력 또한 시급히 요구되고 있다. 이러한 노력의 일환으로 해운 업계에서는 항내에서 유발되는 선박 기인 온실가스 배출량 중 탄소에 대한 배출량 감축과 선박운항 비용 절감을 위한 친환경 항만 체계 구축 방안이 활발히 논의되고 있다. 이 논문에서는 탄소 배출량 감축 및 친환경 항만 체계 구축의 기초 연구로 정박 중인 선박에 자체 생산 전력을 공급하는 대신 육상전력을 공급하는 방안을 모색하였다. 이를 위하여 실제 운항중인 목포해양대학교의 실습선 새누리호를 대상으로 정박 중인 선박이 육상전력을 사용함으로써 얻을 수 있는 환경적 비용적 효과에 관해 고찰하였다. 연구 결과 육상전력을 사용한 경우에 $CO_2$ 배출량은 약 32.5%가 감소되었고, 운항비용은 약 33%가 절감된 것으로 나타났다.

• Journal of Korea Trade
• /
• 제25권2호
• /
• pp.196-219
• /
• 2021

Purpose - We attempted to empirically verify the effects of managerial attributes on cost stickiness in exporters. Exporters are often affected not only by external factors such as exchange rate but also by internal factors such as managerial attributes regarding their business activities. Because cost stickiness is the product of a manager's decision-making, it has been considered that managerial attributes have a great influence on the behavior. Therefore, our study was intended to find out whether cost stickiness shows differentiated aspects depending on managerial attributes in exporters. Design/methodology - We considered two managerial attributes: CEO power and managerial overconfidence. First, CEO power was measured as CEO pay slice. In addition, managerial overconfidence was measured based on three methodologies presented by previous studies. To measure cost stickiness, we used multiple methodologies presented by prior research. Findings - The results of our empirical analysis are as follows. First, in export firms, the greater CEO power is, the greater cost stickiness is. This result suggested that export managers with great influence little respond to temporary sales decrease promptly, little reduce related production costs flexibly in preparation for future sales recovery, but leave room to endure costs for idle resources. Second, the greater managerial overconfidence is, the greater cost stickiness is. This result indicated that export managers with great overconfidence on their decision-making often view the prospect for sales recovery positively; therefore, they little respond to temporary sales decrease immediately, little reduce related production costs flexibly for future sales recovery, but leave room to endure costs for idle resources. Third, export managers with great influence in their businesses and great overconfidence in their decision-making tend to show relatively great cost stickiness. The results proposed that the combination of the two factors functions to make cost stickiness greater. Originality/value - Our study is differentiated from extant studies in that we provided empirical evidence of the effects of managerial attributes on their business activities in exporters. Specifically, we verified the effects of managerial attributes on cost stickiness in Korean exporters. The results of our study are expected to contribute to providing useful information for exporters and start-ups.

• Clinical Endoscopy
• /
• 제57권1호
• /
• pp.105-111
• /
• 2024

Background/Aims: The pancreatic pseudocyst (PP) is a type of fluid collection that typically develops as a delayed complication of acute pancreatitis. Drainage is indicated for symptomatic patients and/or associated complications, such as infection and bleeding. Drainage modalities include percutaneous, endoscopic, laparoscopic, and open drainage. This study aimed to assess trends in the utilization of different drainage modalities for treating PP from 2016 to 2020. The trends in mortality, mean length of hospital stay, and mean hospitalization costs were also assessed. Methods: The National Inpatient Sample database was used to obtain data. The variables were generated using International Classification of Diseases-10 diagnostic and procedural codes. Results: Endoscopic drainage was the most commonly used drainage modality in 2018-2020, with an increasing trend over time (385 procedures in 2018 to 515 in 2020; p=0.003). This is associated with a decrease in the use of other drainage modalities. A decrease in the hospitalization cost for PP requiring drainage was also noted (29,318 United States dollar [USD] in 2016 to 18,087 USD in 2020, p<0.001). Conclusions: Endoscopic drainage is becoming the most commonly used modality for the treatment of PP in hospitals located in the US. This new trend is associated with decreasing hospitalization costs.

• 한국항만경제학회지
• /
• 제25권3호
• /
• pp.321-338
• /
• 2009

본 연구는 부산항과 인천항간 컨테이너 연안운송이 중단된 배경을 비용구조와 수입 배분의 특성, 시장에서 기업의 행동상 제약으로 구분하여 살펴보았다. 이를 위해 연안운송의 국내물류체계와 연관된 선박 운영비용의 구조를 고찰하고 비용함수를 추정하였다. 또한 연안선사내 운영수입의 배분비율을 살펴보았으며, 144TEU급과 215TEU 급 선박의 평균수입을 산정하였다. 경제적 제약 측면에서는 기업의 이윤 극대화 혹은 손실 최소화라는 목표를 전제로, 연안운송의 중단 원인을 찾으려 노력하였다. 연구 결과, 연안운송은 운영비용 측면에서 최대적재능력에 가까운 적재율을 실현하고 대형선박을 투입할 경우 규모의 경제를 실현할 수 있었다. 운영수입에서는 트럭운송시장의 영향, 복잡한 물류체계에 따른 낮은 평균수입으로 적자가 누적될 가능성이 있었다. 경제적으로는 평균수입이 평균비용보다 낮아, 연안선사가 서비스를 중단하였던 것으로 판단되었다. 따라서 전용선박에 의한 연안운송이 지속되려면 정부 등의 보조금 지원이 필요하다고 판단된다.