• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.20 no.7
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• pp.651-657
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• 2010

Previous experimental results performed by many researchers for a couple of decades in South Korea have shown that an absorbing sheet inserted in a conventional floating slab system for thermal insulation or vibration absorption may amplify the vibration of the slab system at specific frequency ranges depending on the material properties of the sheet. The amplified vibration, consequently, results in the heavy weight floor impact noise exceeding the sound level limit for an apartment house, 50 dB. In this study, the amplification mechanism is examined through numerical analysis and a new slab system is proposed to reduce the amplification and control the noise. The new slab system consists of studs connecting the base slab and upper concrete finishing yielding the dramatically increased stiffness of the slab. The numerical simulation is performed to investigate the effect of the slab system with studs on the vibration and noise control. The results show that the performance of the slab is sensitive to the number and location of studs, and the heavy weight floor impact noise can be reduced up to 6~7 dB compared to the conventional slab system at the optimal stud location.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2013.05a
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• pp.1407-1408
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• 2013

• Journal of the Korea Safety Management & Science
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• v.2 no.4
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• pp.19-32
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• 2000

Assignable causes producing temporary deviation from the underlying system can influence on process adjustment and process monitoring in dynamic feedback control system. In this paper, the impact of assignable causes on EWMA forecasts and process adjustment which is based on the EWMA forecasts are derived for optimum control methods.

• 제어로봇시스템학회:학술대회논문집
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• 1993.10a
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• pp.1147-1154
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• 1993

This paper introduces a case of SCADA System replacing from centralized processing system to distributed/open architecture system. The cons and pros of the distinctive two system configurations were studied and the requirements of new system that would be enable to easily follow 21 century's technical and operational inovation were presented.

• The Korean Journal of Emergency Medical Services
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• v.5 no.1
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• pp.147-164
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• 2001

The purpose of this study was to examine the hypothetical model designed to explain the post-traumatic stress and burnout in firefighters. Six exogenous variables such as career, control, impact mobilization frequency, life event, work burden, social support, and four endogenous variables, eg., mobilization impact, coping, post-traumatic stress, burnout were considered for the study. The target population for the distribution of the questionnaire was 428 firefighters in Daejeon, Chungnam Province, Seoul and Kyonggi Province. The data was collected about five weeks, July 12-August 25, 1999. The survey instrument was 8 control items by Seo(1995), 10 life event items by Brugha and Cragg(1990), 20 work burden items by Choi(2000), 12 social support items by Park(1985), post-traumatic stress of 17 items by Foa et al.(1998) and 45 items by Kang(1997). The reliability of the survey instrument and the cronbach's alpha was .62 - .93 level. SAS PC Program and LISREL 8.12a program were used for descriptive statistics and linear structural relationship(LISREL) modeling. Based on the data collected, the following results were obtained. 1. The overall fit of the hypothetical model to the data was good (${\chi}^2=54.65$ [df=17, p=0.000007], RMSEA=0.07, standardized RMR=0.03, GFI=0.98, AGFI=0.91, NFI=0.90, NNFI=0.75). 2. After considering statistical significance and theoretical meaningfulness of paths of the model, a modified model was sought. Compared to the hypothetical model, the modified model has become parsimonious and had a better fit to the data(${\chi}^2=55.90$ [df=20, p=0.0003], RMSEA=0.06, standardized RMR=0.03, GFI=0.98, AGFI=0.93, NFI=0.90, NNFI=0.80). 3. The results of statistical testing of hypotheses were as follows: (1) Work burden, career had a significantly direct effect on mobilization impact. These variables explained 9% of the total variance of mobilization impact. (2) Control, social support, work burden, mobilization impact had a significantly direct effect on coping. These variables explained 15% of the total variance of coping. (3) Control, work burden, social support, coping had a significantly direct effect on post-traumatic stress. These variables explained 49% of the total variance of post-traumatic stress. (4) Coping, post-traumatic stress had a significantly direct effect on burnout. These variables explained 60% of the total variance of burnout.

• Korea Journal of Hospital Management
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• v.7 no.4
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• pp.57-101
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• 2002

These days, the environment of hospital marketing is changing rapidly. The level of expectation and demand of patients have become greater and more diversified, and patients have more alternatives in selecting hospitals. The standard of hospital selection and the type of using hospital have been changed, and competition among hospitals has been accelerated due to the opening of the medical market through globalization. Accordingly, differentiation strategies are critical in hospital marketing. The quality of medical service oriented toward patient satisfaction becomes a strong strategic weapon to secure a hospital's competitive advantage. Therefore, marketing and communication strategies should be focused on patient-oriented, rather than hospital-oriented. Considering the changes in the hospital environment and the increase in the patients' expectation level, this study categorizes doctors' communication styles into four different ones: trust-type, professional-type, cooperation-type, and control-type. The effects of these communication styles on patient satisfaction were empirically examined. The moderating roles of the patient's characteristics and clinical characteristics between the doctors' communication styles and patient satisfaction were also investigated to find out managerial implications for hospital management. To achieve such goals, data were collected from patients of 12 general hospitals in Busan. The data were analyzed to test research hypotheses that examine 1) the relationships between doctors' communication styles and patient satisfaction, 2) the moderating roles of the patient characteristics and clinical characteristics in the research model, and 3) the impact of patient satisfaction on positive word-of-mouth and repurchase. The following summarizes the major results of this research. First, the data showed that patient satisfaction varied across doctors' communication styles. Trust-type style had the strongest impact on patient satisfaction while control-type style had the weakest influence on patient satisfaction. Professional-type style and cooperation-type style also had positive effects on patient satisfaction but the impact of the two are not statistically different. Second, significant differences in terms of patient satisfaction were found depending upon demographic variables such as gender, marital status, age, occupation, and education. Patient satisfaction, however, was consistent across varying income groups. Third, patients' medical insurance types were also related to patient satisfaction. It implies that a doctor may need to use different communication styles depending on a patient's medical insurance type. Fourth, out-patient and in-patient showed a different level of satisfaction with varying communication styles. Fifth, highly professional knowledge and strong control can influence patient satisfaction depending on the characteristics of the patient treatment field. Sixth, patient satisfaction were proved to have significantly positive effects on word-of-mouth and repurchase. The implications drawn from this study must be tempered by its limitations. First of all, the subjects used in this study were patients in Busan and small- and medium-size hospitals were excluded from the research. Therefore, future research should examine the research model by using a variety of hospitals and clinics throughout Korea. Another research agenda has to do with finding more determinant and moderating variables which will increase an explanatory power of the model. In short, this study may be the first empirical research that investigates the effects of doctors' communication styles on patient satisfaction. Interestingly enough, the results showed that each communication style had a unique impact on patient satisfaction. The findings from this research can be very useful in developing hospital marketing strategies.

• Asian Pacific Journal of Cancer Prevention
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• v.16 no.17
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• pp.7813-7818
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• 2015

Background: Radiotherapy plays an important role as adjuvant treatment in locally advanced breast cancer and in those patients who have undergone breast-conserving surgery. This study aimed to investigate the prognostic impact of adjuvant radiation on oncologic outcomes in elderly women with breast cancer. Materials and Methods: In this retrospective study, we reviewed and analyzed the characteristics, treatment outcome and survival of elderly women (aged ${\geq}60years$) with breast cancer who were treated and followed-up between 1993 and 2014. The median follow up for the surviving patients was 38 (range 3-207) months. Results: One hundred and seventy-eight patients with a median age of 74 (range 60-95) years were enrolled in the study. Of the total, 60 patients received postoperative adjuvant radiation (radiation group) and the remaining 118 did not (control group). Patients in the radiation group were significantly younger than those in the control group (P value=0.004). In addition, patients in radiation group had higher node stage (P value<0.001) and disease stage (P=0.003) and tended to have higher tumor grade (P=0.031) and received more frequent (P value<0.001) adjuvant and neoadjuvant chemotherapy compared to those in the control group. There was no statistically significant difference between two groups regarding the local control, disease-free survival and overall survival rates. Conclusions: In this study, we did not find a prognostic impact for adjuvant radiation on oncologic outcomes in elderly women with breast cancer.

• Journal of Institute of Control, Robotics and Systems
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• v.19 no.6
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• pp.527-533
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• 2013

BCI (Brain-Computer Interface) is a system that transforms a subject's brain signal related to their intention into a control signal by classifying EEG (electroencephalograph) signals obtained during the imagination of movement of a subject's limbs. The BCI system allows us to control machines such as robot arms or wheelchairs only by imaging limbs. With the exact same experiment environment, activated brain regions of each subjects are totally different. In that case, a simple approach is to use as many channels as possible when measuring brain signals. However the problem is that using many channels also causes other problems. When applying a CSP (Common Spatial Pattern), which is an EEG extraction method, many channels cause an overfitting problem, and in addition there is difficulty using this technique for medical analysis. To overcome these problems, we suggest an optimal channel selection method using a BPSO (Binary Particle Swarm Optimization), BPSO with channel impact factor, and GA. This paper examined optimal selected channels among all channels using three optimization methods and compared the classification accuracy and the number of selected channels between BPSO, BPSO with channel impact factor, and GA by SVM (Support Vector Machine). The result showed that BPSO with channel impact factor selected 2 fewer channels and even improved accuracy by 10.17~11.34% compared with BPSO and GA.

• Journal of the Korea Safety Management & Science
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• v.7 no.5
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• pp.213-231
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• 2005

Assignable causes producing temporary deviation from the underlying system can influence on process adjustment and process monitoring in dynamic feedback control system. In this paper, the influence of assignable causes on EWMA forecasts and compensatory variables are derived for a dynamic feedback control system. An example is presented to confirm the impact numerically through the analysis of a data.

• Nuclear Engineering and Technology
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• v.54 no.11
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• pp.4111-4124
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• 2022

The control rod drive system is critical to the reactor's reliable operation. The performance of its control system and mechanical system will gradually deteriorate because of operational and environmental stresses, thus increasing the reactor's operational risk. Currently there are few researches on the aging-related degradation of the entire control rod drive system. Because it is difficult to quantify the effect of various environmental stresses and establish an accurate physical model when multiple mechanisms superimposed in the degradation process. Therefore, this paper investigates the aging-related degradation of a control rod drive system by integrating Dynamic Object-Oriented Bayesian Network and Hidden Markov Model. Uncertainties in the degradation of the control system and mechanical system are addressed by using fuzzy theory and the Hidden Markov Model respectively. A system which consists of eight control rod drive mechanisms divided into two groups is used to demonstrate the method. The aging-related degradation of the control rod drive system is analyzed by the Bayesian inference algorithm based on the accelerated life test data, and the impact of different operating schemes on the system performance is also investigated. Meanwhile, the components or units that have major impact on the system's performance are identified at different operational phases. Finally, several essential safety measures are suggested to mitigate the risk caused by the system degradation.