• Transactions of the Korean Society of Automotive Engineers
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• v.7 no.5
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• pp.1-8
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• 1999

This paper describes the method for detection of the misfired cylinder by analysis of the variation of pressure occurred in exhaust manifold on an MPI gasoline engine. Misfired cylinder(s) cause a loss of power, an increase of fuel consumption and exhaust emission and vibration is caused by unsteady torque. Therefore early detection and correction of misfired cylinder(s) play a very important role in the proper performance and the exhaust emission. The method is a comparison of integration pressure index during the period of a blowdown in the displacement period. Experimental results showed that the method, using the variation of pressure in the exhaust manifold is proven to be effective in the detection of single cylinder or multiple cylinders misfire on the gasoline engine regardless of the engine revolutions. In addition, this method, using the variation of pressure in the exhaust manifold is a very easy and accurate method compared with other methods.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.26 no.5
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• pp.750-756
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• 2002

The effect of equivalence ratio and velocity on the stability of flame in dump combustor was studied in an atmospheric pressure, laboratory scathe dump combustor operating natural gas. Traditionally, peak-to-peak pressure, fluctuation of the heat release rate and Rayleigh index were used to find and control the combustion instability. Cross correlation coefficients, Ci,j which is defined as the normalized value of the integration of the product of two of the mixer pressure, dump plane pressure and heat release rate, are introduced to see whether the flame is stable or not. Ci,j shows more sensitive to combustion status than Rayleigh index in steadily burning flame. Also, the result indicates that the amplitude of Ci,j between heat release and mixer pressure goes up before the flame at the rich de-stabilizing equivalence ratio near $\psi$=0.85. t means Ci:j at this case has a potential to detect the de-stablizing moment in prior to becoming unstable in dump combustor.

• Journal of the Korean Institute of Landscape Architecture
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• v.37 no.4
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• pp.1-11
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• 2009

This study was intended to set development priorities for five undeveloped neighborhood parks scattered throughout the downtown area of Cheongju City using a PDPI(Park Development Pressure Index). In order to calculate the PDPI, this study employed an additive integration method. The PDPI was graded from 1 to 5, based on the evaluation scores in accordance with nine indicators selected through literature reviews and interviews with public officials. The indicators have been classified into three categories: physical environment, utilization possibility, and facility distribution. The indicators are as follows: 1) 'altitude and inclination' and 'NDVI' as physical environment indicators; 2) 'ratio of residential area', 'forecasted utility population', 'undeveloped period', 'redevelopment near parks', 'ratio of area divided by main streets', reflecting utilization possibility; and 3) 'Distance between Neighborhood Parks' and 'Distribution of alternative facilities' as facility distribution. The following results were found: 1) three neighborhood parks including 'Sagic 2', 'Sachen', and 'Dangsan' were ranked in the first grade of PDPI; and, 2) one neighborhood park 'Samsungdang' was ranked in the fifth grade of PDPI. The above results mean that among undeveloped neighborhood parks, three have been exposed to extremely strong park development pressure, and that while two neighborhood parks have had strong exposure to park development pressure due to potential users according to their close location to Sagic Ro, an east-west main axis of Cheongju City, one neighborhood park has had weak exposure to development pressure because of the close location to 'Chuungbuk National University' and a lack of residential areas, showing a low possibility for development.

• Korea Journal of Hospital Management
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• v.7 no.3
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• pp.102-120
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• 2002

The purpose of study is to understand human-technology integration mechanism by using the study model that takes the core concept and motivation assumptions of technology acceptance model(TAM) into account. This study identifies three motivation mechanisms in adopting or using computer mediated communication(CMC) tool for work. The mechanism comprises with extrinsic, extrinsic motivation, and subjective norm pressure. One hospital with 430 beds and 367 human power was identified and we administered the questionnaire during their work hours. There is 32.4% response rate. The fitting index of the study model surpass the acceptable level, GFI = .980 for none-users, GFI =.986 for users, NNFI = .973 for none-users, and NNFI = .989 for users. In the case of none-users, perceived ease of use determines perceived usefulness that explains behavioral intention to use. As a result, adotpers' usage motivation is based on extrinsic motivation that does not consider their affective factor, attitude, in use of CMC. Users considers their attitudes as the mediating factor of all behavioral beliefs for using CMC continually. Thus, users are likely to depend their adoption behaviors on their affective factor. Moreover, users' behavioral intention is subject to pressures of use from other persons who are important to them, such as supervisor, director, or boss. Achieving human-technology integration in a hospital may cause cost saving and work efficiency. However, the success of information system should base on a profound understanding of employees' adoption behaviors in rejecting, adopting, using, continually using of IT, and organization culture in using IT.

• International journal of advanced smart convergence
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• v.12 no.3
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• pp.89-103
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• 2023

Obstructive sleep apnea (OSA) is one of the most prevalent sleep disorders that can lead to serious consequences, including hypertension and/or cardiovascular diseases, if not treated promptly. Continuous positive airway pressure (CPAP) is widely recognized as the most effective treatment for OSA, which needs the proper titration of airway pressure to achieve the most effective treatment results. However, the process of CPAP titration can be time-consuming and cumbersome. There is a growing importance in predicting personalized CPAP pressure before CPAP treatment. The primary objective of this study was to optimize the CPAP titration process for obstructive sleep apnea patients through EEG feature engineering with machine learning techniques. We aimed to identify and utilize the most critical EEG features to forecast key OSA predictive indicators, ultimately facilitating more precise and personalized CPAP treatment strategies. Here, we analyzed 126 OSA patients' PSG datasets before and after the CPAP treatment. We extracted 29 EEG features to predict the features that have high importance on the OSA prediction index which are AHI and SpO2 by applying the Shapley Additive exPlanation (SHAP) method. Through extracted EEG features, we confirmed the six EEG features that had high importance in predicting AHI and SpO2 using XGBoost, Support Vector Machine regression, and Random Forest Regression. By utilizing the predictive capabilities of EEG-derived features for AHI and SpO2, we can better understand and evaluate the condition of patients undergoing CPAP treatment. The ability to predict these key indicators accurately provides more immediate insight into the patient's sleep quality and potential disturbances. This not only ensures the efficiency of the diagnostic process but also provides more tailored and effective treatment approach. Consequently, the integration of EEG analysis into the sleep study protocol has the potential to revolutionize sleep diagnostics, offering a time-saving, and ultimately more effective evaluation for patients with sleep-related disorders.

• Korean Journal of Poultry Science
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• v.42 no.3
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• pp.247-256
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• 2015

There are approximately 1,500 broiler farms in Korea, each raising 55,000 birds. Ninety-five percent of the farms are contracted with Integration Company. According to the Korean broiler performance index, broilers in Korea are marketed at 32 days with 1.52 kg of body weight. In contrast, the market age and body weight of broilers are 47 days/2.8 kg in the United States and 42 days/2.5 kg in Europe. Because of the younger market age of the Korean broiler, the pre-starter feed is important. Chicks exhibit poor absorption of dietary nutrients up to 7 days after hatching due to an immature digestive system and low enzyme secretion rate and activity. At the beginning of hatching, chicks obtain their nutrients from the egg yolk sac. It is highly recommended that chicks, after consuming the nutrients in the egg yolk sac, are given supplemented pre-starter feed to increase early growth rates and improve the performance of broiler production. Pre-starter nutrient requirements are not expressed in NRC, so Korean feeding standards for poultry and commercial breeding companies determine the nutrient requirements of pre-starter broiler chickens. Three approaches are followed to formulate specially designed pre-starter feeds for broiler chicks: (i) selective use of raw materials, (ii) proper standards of nutrient supply, and (iii) application of feed additives such as exogenous enzymes. In the selection of raw materials, those with high digestibility can be used. The absorption rate of carbohydrates in grains can be increased through feed processing at high temperature and high pressure. Soy proteins and fish meal can also be added as protein sources. As an energy source, vegetable oils are preferred over animal fats because of the former's high digestibility. It is suggested that the levels of proteins and amino acids are higher in pre-starter feed than in starter feed. With regard to energy, the sources of energy are more important than the levels of energy in feed. Feed additives such as exogenous enzymes can be used to improve nutrient digestibility. In addition, organic acids and plant extracts can be used as alternatives to animal growth promoters to stimulate immunity and prevent diseases. The growth performance of broilers is affected by various factors, such as management and disease control, in addition to the nutritional strategy; however, nutritional strategies play an important role in improving the productivity of broilers. Therefore, nutritional strategies, along with management and disease control, are required for improving the productivity of broilers in Korea.