• 대한산업공학회지
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• 제43권3호
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• pp.176-183
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• 2017

In recent years, studies about multitasking becomes more important. During multitasking, operators can feel frustration when they are interrupted during the task and frustration can affect operator's emotional state and performance. However there is no research on measuring the frustration quantitatively in multitasking environment. In this paper, we suggested quantitative measurement of frustration during multitasking. In order to measure the frustration, we made a mathematical representation with emotional decay model and the initial intensity of frustration based on cognitive closure theory. The amount of initial intensity could be represented as the ratio of actual remaining time to expected remaining time. By the experiment, we measured the frustration during the experiment and compared this values with values of frustration dimension of NASA-TLX. Finally we got the linear regression model with a good accuracy ($R^2=0.986$). This study contributes to measuring the emotion quantitatively by the relation of expected and actual remaining time in multitasking environment.

• Journal of the Korean Statistical Society
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• 제7권2호
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• pp.101-104
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• 1978

This paper considers the problem of estimating $\hat{\beta}$ in the case errors occur in observing the values of q-variables $X_1, X_2, ..., X_q$. The approximated estimator $\hat{\beta}(e)$ is obtained and its expected value, bias and covariance matrix are studied.

• 지식경영연구
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• 제9권4호
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• pp.113-125
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• 2008

Net present value (NPV) and return on investment (ROI) are commonly used to evaluate investment in new technologies. Sometimes, however, measuring the value of investment in new IT becomes very difficult due to its wide scope of application coupled with embedded options in its adoption. Therefore, comprehensive but easily understandable methodologies are needed to solve the complicated problems resulting from the complexity of new technologies. This paper employs a real option analysis to evaluate RFID adoption in the supply chain. Real options analysis should be a better way to evaluate a disruptive technology like RFID. However, the pure (probabilistic) real option rule characterizes the present value of expected cash flows and the expected costs by a single number, which is not realistic in many cases. To solve the problem, this paper considers the real option rule in a more realistic setting, namely, when the present values of expected cash flows and expected costs are estimated by trapezoidal fuzzy numbers.

• 한국지능시스템학회논문지
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• 제15권1호
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• pp.98-103
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• 2005

본 논문에서는 구간수치 확률변수와 퍼지수치 확률변수를 생각하고 이들의 쇼케이 적분을 조사한다. 이러한 성질들을 이용하여 퍼지수치 확률변수의 르베그적분의 일반화인 퍼지수치 확률변수의 쇼케이 기대값을 정의한다. 특히 이들의 응용에 관한 예제들을 다룬다.

• 한국의류학회지
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• 제25권4호
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• pp.773-782
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• 2001

This study was to investigate the value changes in Korean women by analyzing the ads of womens magazines. The contents of ads were classified into two types of values: general and consumption values. The general values, composed of inner-directedness and outer-directrdness, might predict consumer behavior in general. The consumption values, utilitarians and hedonic, were expected to affect the consumer purchasing attitude to a specific product. Factors affecting the cultural values were per capita income and womens social status. Total 2969 illustrated ads with verbal theme from 32 Korean womens magazines were used. The content analysis, chi-square test, logistic regression were done for the analysis. The results showed that inner-directedness was dominant general value in Korean womens culture and increased over time. Younger consumers were more inner-directed than older ones were, and inner-directed values increased with income growth. For the consumption values, utilitarian values were higher than hedonic ones and went up over time. For the product types, utilitarian ads were frequent in cosmetics while hedonic ads were high for apparels. Those results implied that Korean womens culture became more inner-directed with increased income. Also consumption values were likely to differ between product groups. Per capita income was shown to increase inner-directedness while womens social status was to increase outer-directedness.

• 대한수학회지
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• 제39권2호
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• pp.205-219
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• 2002

We deride formulas for the expected values $\mu$(n) of the independent domination numbers of a random planted plane tree and a random trivalent tree with n vertices, respectively, and we determine the asymptotic behavior of $\mu$(n) as n goes to infinity.

• Communications for Statistical Applications and Methods
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• 제7권3호
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• pp.687-698
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• 2000

An identification method is proposed in order to detect more than one outlying cells in multi-way contingency tables. The iterative proportional fitting method is applied to get expected values of several suspected outlying cells. Since the proposed method uses minimal sufficient statistics under quasi log-linear models, expected counts of outlying cells could be estimated under any hierarchical log-linear models. This method is an extension of the backwards-stepping method of Simonoff(1988) and requires les iteration to identify outlying cells.

• 보건행정학회지
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• 제31권4호
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• pp.508-517
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• 2021

Background: After the first case of coronavirus disease 2019 (COVID-19) in January 2020, Korea has experienced three waves in 2020. This study aimed to analyze changes in health care utilization according to the period of the 1st to 3rd waves of the COVID-19 pandemic. Methods: We analyzed 3,354,469,401 national health insurance claims from 59,104 medical facilities between 2017 and 2020. Observed-to-expected ratios (O:E ratio) with data from 2017 to 2019 as expected values and data from 2020 as observed values were obtained to analyze changes in medical utilization. T-test was used to test whether the difference of observed and expected values was statistically significant. Results: In 2020, the O:E ratio was 0.894, indicating a decrease in health care utilization overall during the pandemic. The O:E ratio of the 1st wave was 0.832, which was lower than those of the second (0.886) and third (0.873) waves. Health care utilization decreased relatively more among outpatient, women, children and adolescents, and health insurance patients. And health care utilization decreased more in small medical facilities and in Daegu and Gyeongbuk during the first wave. During the pandemic, the O:E ratios of respiratory diseases were 0.486-0.694, while chronic diseases and mental diseases were more than 1.0. Conclusion: Health care utilization decreased during the COVID-19 pandemic overall, and there were differences by COVID-19 waves, and by the characteristics of patients and medical facilities. It is necessary to understand the cause of changes in health care utilization in order to cope with the prolonged COVID-19 pandemic.

• Design & Manufacturing
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• 제16권4호
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• pp.52-59
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• 2022

Currently, Korea is an aging society and is expected to become a super-aged society in about four years. X-ray devices are widely used for early diagnosis in hospitals, and many X-ray technologies are being developed. The development of X-ray device technology is important, but it is also important to increase the reliability of the device through accurate data management. Sensor nodes such as temperature, voltage, and current of the diagnosis device may malfunction or transmit inaccurate data due to various causes such as failure or power outage. Therefore, in this study, the temperature, tube voltage, and tube current data related to each sensor and detection circuit of the diagnostic X-ray imaging device were measured and analyzed. Based on QC data, device failure prediction and diagnosis algorithms were designed and performed. The fault diagnosis algorithm can configure a simulator capable of setting user parameter values, displaying sensor output graphs, and displaying signs of sensor abnormalities, and can check the detection results when each sensor is operating normally and when the sensor is abnormal. It is judged that efficient device management and diagnosis is possible because it monitors abnormal data values (temperature, voltage, current) in real time and automatically diagnoses failures by feeding back the abnormal values detected at each stage. Although this algorithm cannot predict all failures related to temperature, voltage, and current of diagnostic X-ray imaging devices, it can detect temperature rise, bouncing values, device physical limits, input/output values, and radiation-related anomalies. exposure. If a value exceeding the maximum variation value of each data occurs, it is judged that it will be possible to check and respond in preparation for device failure. If a device's sensor fails, unexpected accidents may occur, increasing costs and risks, and regular maintenance cannot cope with all errors or failures. Therefore, since real-time maintenance through continuous data monitoring is possible, reliability improvement, maintenance cost reduction, and efficient management of equipment are expected to be possible.

• Communications for Statistical Applications and Methods
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• 제17권6호
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• pp.755-765
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• 2010

혼합분포의 분류문제에서 비용함수를 고려한 분류점은 최소 기대비용이라는 측면에서 최적이다. 비용에 관한 어떠한 정보가 주어지지 않은 경우에 ROC곡선을 이용하여 분류정확도 측도인 전체정확도와 진실율이 최대일 때의 분류점에 대응하는 기대비용에서의 비용비율을제안하고, 최소 기대비용의 비용비율과의 관계를 설명한다. 그리고 비용곡선을 이용하여 분류정확도 측도들에 기반하는 최소 기대비용에서의 비용비율을 제안하였고 이 비용비율은 대표적인 두 종류의 분류정확도가 최대일 때의 기대비용에 대한 비용비율들 사이에 존재하며, 최소 기대비용에서의 비용비율에 수렴하는 것을 발견하였다. 본 연구는 기대비용과 정규화된 기대비용을 최소화할 때의 비용비율과 분류정확도가 최대일 때의 비용비율들의 관계를 토론한다.