• 대한산업공학회지
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• 제19권1호
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• pp.61-71
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• 1993

We focus on a way of combining the Monte Calro methods of antithetic variates and control variates to reduce the variance of the estimator of the mean response in a simulation experiment. Combined Method applies antithetic variates (partially) for driving approiate stochastic model components to reduce the vaiance of estimator and utilizes the correlations between the response and control variates. We obtain the variance of the estimator for the response analytically and compare Combined Method with control variates method. We explore the efficiency of this method in reducing the variance of the estimator through the port operations model. Combined Method shows a better performance in reducing the variance of estimator than methods of antithetic variates and control variates in the range from 6% to 8%. The marginal efficiency gain of this method is modest for the example considered. When the effective set of control variates is small, the marginal efficiency gain may increase. Though these results are from the limited experiments, Combined Method could profitably be applied to large-scale simulation models.

• 대한수학교육학회지:학교수학
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• 제6권2호
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• pp.135-151
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• 2004

수학교과서의 대부분을 차지하고 있는 문장제가 실생활 상황을 반영하여 제시되기보다는 문제에서 주어진 숫자와 연산의 기계적인 조합을 통해 문제를 해결하게 하는 경향으로 나타나는 문제점은 계속해서 지적되어 왔다. 이는 수학교육이 지향하고 추구하고 있는 실제적 상황에서의 문제 해결력 함양을 위해서 간과할 수 없는 지적이라고 보여진다. 이에 본 연구에서는 초등학생을 대상으로 이전에 보아왔던 정형화되어 있는 문제들보다는 현실적인 상황을 고려한 문장제에 대해 그들이 얼마나 현실적인 측면을 고려하여 반응하는지 파악하고자 하였다. 이를 위한 문항들은 덧셈, 뺄셈, 곱셈, 나눗셈을 포함한 연산과 올림의 개념을 내포하는 문제들로 이루어졌다. 그 결과, 대부분의 초등학생들이 현실적인 문장제에 대해 현실성을 고려하여 문제를 해결하지 못하는 것으로 나타났다.

• 대한산업공학회지
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• 제19권2호
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• pp.53-64
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• 1993

Successful completion of a visual task in a predetermined time is very crucial to many operations such as piloting an aircraft. Although existing ergonomic interface models often provide a function of vision tests, it determines only the visibility at any given location. To complement this problem in existing models, the isoresponse time region considering the factors related to visual tasks is presented. Using a multiple regression model, equal response time regions were obtained within which mean response time is expected to be the same and is asymmetrical in shape. Among the factors considered, expectancy significantly decreased response time, and when cued, the effects of field heterogeneity, target uncertainty, density, size contrast and peripheral position on search time were less significant than those in unexpected cases. Response time and error rate, gender and visual acuity were not significantly correlated, and response time and age was positively correlated. These results are expected to be directly applicable to designing various visual tasks in real-life situations.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제15권5호
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• pp.1909-1928
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• 2021

At present, the Colombian government shares information on threats or vulnerabilities in the area of cybersecurity and cyberdefense, from other government agencies or departments, on an ad-hoc basis but not in real time, with the surveillance entities of the Government of the Republic of Colombia such as the Joint Command of Cybernetic Operations (CCOCI) and the Cybernetic Emergencies Response Team of Colombia (ColCERT). This research presents the MS-CSIRT (Management System Computer Security Incident Response Teams) methodology, that is used to unify the guidelines of a CSIRT towards a joint communication command in cybersecurity for the surveillance of Information Technology (IT), Technological Operations (TO), Internet Connection Sharing (ICS) or Internet of Things (IoT) infrastructures. This methodology evaluates the level of maturity, by means of a roadmap, to establish a CSIRT as a reference framework for government entities and as a guide for the areas of information security, IT and TO to strengthen the growth of the industry 4.0. This allows the organizations to draw a line of cybersecurity policy with scope, objectives, controls, metrics, procedures and use cases for the correct coordination between ColCERT and CCOCI, as support entities in cybersecurity, and the different companies (ICS, IoT, gas and energy, mining, maritime, agro-industrial, among others) or government agencies that use this methodology.

• 한국식생활문화학회지
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• 제38권3호
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• pp.163-175
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• 2023

This study aimed to examine the operations of school food services to prevent the spread of coronavirus disease 2019 (COVID-19) in schools nationwide. The survey data on school food service operations targeting nutrition teachers and nutritionists at 1,023 schools in 2020 and 1,177 schools in 2021 were used. The year 2021 saw an increase compared to 2020 in the following: 'average days to be served with meals for a year (144.5 vs. 184.7)', 'provided meals to all students (92.3% vs. 96.6%)', 'utilization of additional staff for foodservice assistance (33.4% vs. 38.8%)', 'installation of partitions (61.2% vs. 83.8%)', 'provision of general diet (96.1% vs. 99.1%)', and 'use of kitchen utensils (91.3% vs. 95.1%)', 'use of cafeteria water cup (9.9% vs. 31.0%)' and 'use of drinking water in school (46.8% vs. 52.1%)'. Compared to 2020, in 2021, it was confirmed that the school food service operations stabilized due to the increase in the normal school attendance rate and that systems were in place for operations during the COVID-19 pandemic. In the future, it will be necessary to develop manuals and special recipes necessary for responding to infectious diseases, and to operate a manpower pool that can quickly find replacement personnel if required.

• Journal of Power Electronics
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• 제7권4호
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• pp.278-285
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• 2007

Recently, plasma display panels (PDP) have become the most promising candidate in the market for large screen size flat panel displays. PDPs have many merits such as a fast display response time and wide viewing angle. However, there are still concerns about high cost because they require complex driving circuits composed of high power switching devices to generate various voltage waveforms for three operational modes of reset, scan, and sustain. Conventional PDP driving circuits use path switches for voltage separation and a scan switch to offer a scan voltage for reset and scan operations, respectively. In addition, there exist reset switches to initialize PDPs by regulating the wall charge conditions with ramp shaped pulses, which means the necessity of specific power devices for the reset operation. Because power for the plasma discharge accompanied by a large current is transferred to a panel via path switches, high power rating switches are used for path switches. Therefore, this paper proposes a novel low-cost PDP driving scheme achieved by not only eliminating path switches but also merging the function of reset switches into other switches used for sustain or scan operations. The simulated voltage waveforms of the proposed topology and experimental results implemented in a 42-inch panel to demonstrate the validity of using a new gate driver that merges the functions of power switches are presented.

• 대한지역사회영양학회지
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• 제6권5호
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• pp.837-847
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• 2001

The main purposes of this study were to survey and assess the current situation surrounding solid waste generation in school foodservices, to identify and evaluate the measures(reduction and recycling programs) taken by the foodservices for waste disposal, and to suggest appropriate reform measures to improve the current status, especially in terms of environmental preservation. Questionnaires on solid waste management practices were mailed to 206 school foodservice dietitians in the Kyungbuk region : a 64.0%(N = 130) response rate was obtained. While there are food waste and packaging waste generated from the foodservice operations, about a third(34.1%) of the foodservice operations were responsible for the disposal of both the food wastes and packaging wastes. About 90% of school foodservice managers were responsible for managing solid wastes. The primary recycling methods of leftovers generated from the school food service operations were livestock feed(76.0%). About 60.0% of school foodservice managers conducted the food waste reduction program. The performance by the foodservice managers in reducing the food waste was not satisfactory in several fields, such as developing environmentally friendly menus or abiding by the standard recipe, etc. In addition, the government assistance system was not properly working in the food service management. In conclusion, we should focus on increasing the performance in reducing the food waste by the foodservice managers, strengthening and facilitating the government assistance system for the food waste management and to develop education methods and education materials for food waste management.

• 조명전기설비학회논문지
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• 제29권2호
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• pp.19-26
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• 2015

This paper presents design, fabrication, and performance evaluation of a high voltage power supply for Carbon Nano Tube-based planar light sources. The proposed power supply employs an LLC resonant half-bridge converter and a sixfold voltage-multiplying rectifier. Steady-state characteristics of the voltage-multiplying rectifier are analyzed and used to derive the input-to-output voltage conversion ratio of the power supply. The input-to-output frequency response characteristics of the LLC tank circuit are analyzed and utilized in designing a proto-type power supply which produces a 15 KV output using a 400 V input source. The high-voltage transformer is fabricated using a sectional bobbin structure with an epoxy impregnation, in order to provide sufficient insulation for high voltage operations. The performance of the proposed power supply is confirmed with stable and reliable operations at the 15 KV output from no load to nominal load conditions. The proposed power supply is well suited as an electric ballast required stable operations of Carbon Nano Tube-based planar light sources.

• 한국경영과학회:학술대회논문집
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• 한국경영과학회 2000년도 추계학술대회 및 정기총회
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• pp.215-218
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• 2000

Workflow Management System(WfMS) enables corporations to manage business processes efficiently The purpose of this research is to develop a management system that is capable of managing complicated business processes efficiently under distributed environment where many companies or divisions are participating. Run-time encapsulation proposed in this paper is a system design methodology that enables appropriate response to the dynamically changing processes by using nested processes. We have implemented WfMS under Web environment using run-time encapsulation. Run-time encapsulation using nested process is an efficient development methodology for implementing heterogeneous and distributed WfMS under web environment.

• 한국경영과학회:학술대회논문집
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• 대한산업공학회/한국경영과학회 2004년도 춘계공동학술대회 논문집
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• pp.31-34
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• 2004

This research proposes the lateral transshipment policy that can deal efficiently with stockout in the two-echelon distribution network in supply chain. The lateral transshipment policy can be expected for retailers to response the change of customers' demands efficiently. Because of various factors, such as demand fluctuation, replenishment quantity, lead time, and so on, it is very difficult to decide optimal lateral transshipment time and quantity. We suggest the new lateral transshipment policy based on the service level in this research. The efficiency of this policy is proved by simulation experiments.