• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.05a
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• pp.696-700
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• 2007

In case of dome-typed gymnastics training floor, since its form takes shape of the focus of sound, in the occasion when the finishing-material was used with the sandwich panel that prominent in reflexibility, and because the reverberation of sound in indoor is too loud, a smooth practice and teaching is very difficult. As this indoor gymnastics training floor, standing at its character, is required simultaneously the idea communication between the player and the coach, and the acoustic capability regarding to the clearness of music, besides the sport activity, the method to minimize the acoustic defect should be urgently contrived from the stages of design and beginning of construction. On this viewpoint, after investigation on the confidence of the surveyed value and the estimated value using acoustic simulation, and use of the changed finish-material, this thesis intends to design the dome-typed gymnastics training floor that secured the optimized acoustic condition. It is also considered that such result of the study could be utilized as the useful data that enables to improve the retrenchment effect of the construction cost as well as the acoustic performance, by means of the prediction control on the acoustic problem from the stage of design, for the occasion when the similar indoor sport gymnasium is planning to build for the near future.

• Journal of Information Processing Systems
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• v.15 no.3
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• pp.694-706
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• 2019

In this study, we applied the long short-term memory (LSTM) model to classify the cryptocurrency price time series. We collected historic cryptocurrency price time series data and preprocessed them in order to make them clean for use as train and target data. After such preprocessing, the price time series data were systematically encoded into the three-dimensional price tensor representing the past price changes of cryptocurrencies. We also presented our LSTM model structure as well as how to use such price tensor as input data of the LSTM model. In particular, a grid search-based k-fold cross-validation technique was applied to find the most suitable LSTM model parameters. Lastly, through the comparison of the f1-score values, our study showed that the LSTM model outperforms the gradient boosting model, a general machine learning model known to have relatively good prediction performance, for the time series classification of the cryptocurrency price trend. With the LSTM model, we got a performance improvement of about 7% compared to using the GB model.

• Journal of the Society of Naval Architects of Korea
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• v.54 no.6
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• pp.453-460
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• 2017

In order to investigate propulsion efficiency and cavitation characteristics for expanded area ratio variation of the 8800TEU class container propeller, a series of performance tests were conducted at Large Cavitation Tunnel (LCT) and Towing Tank (TT) in KRISO. The cavitation test of the existing propellers (KP1029 & KP1030) was conducted using FRP model ship in LCT. On the basis of LCT test results, it was required to design propeller with better propulsion efficiency and cavitation performance. Two propellers (KP1171 & KP1172) with decreased expanded area ratio were designed on the basis of KP1029 propeller. The new design propellers showed higher efficiency than KP1029 and reasonable cavitation performance. In the future, they will be applied as the standard propeller for the propeller design of the large container ship. Through the performance test and prediction results for the new design propellers, it is thought that high-load propeller with better propulsion efficiency and cavitation performance will be developed constantly.

• Earthquakes and Structures
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• v.8 no.5
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• pp.1017-1038
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• 2015

This paper presents a strengthening method that involves the use of ferrocement jackets and chamfers to relocate plastic hinge for non-seismically designed reinforced concrete exterior beam-column joints. An experimental study was conducted to assess the effectiveness of the proposed strengthening method. Four half-scale beam-column joints, including one control specimen and three strengthened specimens, were prepared and tested under quasi-static cyclic loading. Strengthening schemes include ferrocement jackets with or without skeleton reinforcements and one or two chamfers. Experimental results have indicated that the proposed strengthening method is effective to move plastic hinge from the joint to the beam and enhance seismic performance of beam-column joints. Shear stress and distortion within the joint region are also reduced significantly in strengthened specimens. Skeleton reinforcements in ferrocement provide limited improvement, except on crack control. Specimen strengthened by ferrocement jackets with one chamfer exhibits slight decrease in peak strength and energy dissipation but with increase in ductility as compared with that of two chamfers. Finally, a method for estimating moment capacity at beam-column interface for strengthened specimen is developed. The proposed method gives reasonable prediction and can ensure formation of plastic hinge at predetermined location in the beam.

• Journal of Korean Academy of Nursing Administration
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• v.16 no.3
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• pp.229-239
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• 2010

Purpose: This study aimed to investigate the impact of nursing professionalism on the nursing performance and retention intention among psychiatric mental health nurses. Methods: As a descriptive correlational study, this study sampled 206 psychiatric mental health nurses in six hospitals in Seoul and Gyeonggi area through convenience sampling. Data were collected from March 2 to 31, 2009 using a self-report questionnaire. The collected data were analyzed using SPSS WIN 16.0. Results: In the subscales of professionalism, the 'Sense of calling' had the highest mean score while the 'Professional organization' had the lowest mean score. A significant positive correlation was observed in nursing professionalism, nursing performance and retention intention. According to an analysis on the impact of each subscale of nursing professionalism on nursing performance and retention intention, the 'Sense of calling' and 'Autonomy' were the most significant predictor variable. Conclusion: The results confirmed that the improvement of psychiatric mental health nurses' professionalism increases their nursing performance and retention intention and the 'Sense of calling' and 'Autonomy' are critical prediction factors. It is necessary to come up with a strategy which strengthens nursing professionalism in order to improve psychiatric mental health nurses' performance and retention intention.

• International Journal of Naval Architecture and Ocean Engineering
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• v.7 no.6
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• pp.964-978
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• 2015

Numerous experiments with a scaled pilot facility were carried out to compare the relative bulk transfer performance of three special devices for applications to drilling systems. The pipe diameter for bulk transportation was 3 in., which corresponds to around half of the actual system dimensions. Two different pressures, 3 and 4 bar, were considered to check the relative performance under different pressure conditions at a bulk storage tank. And to make a practical estimation method of the bulk transfer rate at the early design stages of the bulk handling system, a series of experiments were conducted for real scaled bulk handing systems of two drilling vessels. The pressure drops at each pipe element as well as the bulk transfer rates were measured under different operating conditions. Using the measured results, the friction factor for each pipe element was calculated and a procedure for transfer rate estimation was developed. Compared to the measured transfer rate results for other drilling vessels, the estimated transfer rates were within a maximum 15% error bound.

• Atmosphere
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• v.33 no.1
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• pp.33-47
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• 2023

In this study, for the application of observation errors to the Korean Integrated Model (KIM) to utilize the Constellation Observing System for Meteorology, Ionosphere & Climate-2 (COSMIC-2) new satellites, the observation errors were diagnosed based on the Desroziers method using the cost function in the process of variational data assimilation. We calculated observation errors for all observational species being utilized for KIM and compared with their relative values. The observation error of the calculated the Global Navigation Satellite System Radio Occultation (GNSS RO) was about six times smaller than that of other satellites. In order to balance with other satellites, we conducted two experiments in which the GNSS RO data expanded by about twice the observation error. The performance of the analysis field was significantly improved in the tropics, where the COSMIC-2 data are more available, and in the Southern Hemisphere, where the influence of GNSS RO data is significantly greater. In particular, the prediction performance of the Southern Hemisphere was improved by doubling the observation error in global region, rather than doubling the COSMIC-2 data only in areas with high density, which seems to have been balanced with other observations.

• 제어로봇시스템학회:학술대회논문집
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• 2000.10a
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• pp.20-20
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• 2000

Back-propagation neural network (BPNN) is the most prevalently used paradigm in modeling semiconductor manufacturing processes, which as a neuron activation function typically employs a bipolar or unipolar sigmoid function in either hidden and output layers. In this study, applicability of another linear function as a neuron activation function is investigated. The linear function was operated in combination with other sigmoid functions. Comparison revealed that a particular combination, the bipolar sigmoid function in hidden layer and the linear function in output layer, is found to be the best combination that yields the highest prediction accuracy. For BPNN with this combination, predictive performance once again optimized by incrementally adjusting the gradients respective to each function. A total of 121 combinations of gradients were examined and out of them one optimal set was determined. Predictive performance of the corresponding model were compared to non-optimized, revealing that optimized models are more accurate over non-optimized counterparts by an improvement of more than 30%. This demonstrates that the proposed gradient-optimized teaming for BPNN with a linear function in output layer is an effective means to construct plasma models. The plasma modeled is a hemispherical inductively coupled plasma, which was characterized by a 24 full factorial design. To validate models, another eight experiments were conducted. process variables that were varied in the design include source polver, pressure, position of chuck holder and chroline flow rate. Plasma attributes measured using Langmuir probe are electron density, electron temperature, and plasma potential.

• The KIPS Transactions:PartB
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• v.14B no.2
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• pp.127-134
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• 2007

There are many researches about the intelligent stock trading systems with the help of the advance of the artificial intelligence such as machine learning techniques, Though the establishment of the reasonable trading policy plays an important role in the performance of the trading systems most researches focused on the improvement of the predictability. Also some previous works, which treated the trading policy, treated the simplified versions dependent on the predictors in less systematic ways. In this paper, we propose the integrated multiple simulation' as a method of optimizing trading performance of stock trading systems. The propose method is adopted in the NXShell a development environment for neural network based stock trading systems. Under the proposed integrated multiple simulation', we simulate the multiple tradings for all combinations of the neural network's outputs and the trading policy parameters, evaluate the learning performance according to the various metrics and establish the optimal policy for a given prediction module based on the resulting performance. In the experiment, we present the trading policy comparison results using the stock value data from the KOSPI and KOSDAQ.

• Journal of the Korean Institute of Telematics and Electronics B
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• v.30B no.4
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• pp.104-115
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• 1993

The motion compensated coding (MCC) technique, which exploits the temporal redundancies in the moving images with the motion estimation technique,is one of the most popular techniques currently used. Recently, a variable block size(VBS) motion estimation scheme has been utilized to improve the performance of the motion compensted coding. This scheme allows large blocks to the used when smaller blocks provide little gain, saving rates for areas containing more complex motion. Hence, a new VBS motion estimation scheme with a hierarchical structure is proposed in this paper, in order to combine the motion vector coding technique efficiently. Topmost level motion vector, which is obtained by the gain/cost motion estimation technique with selective motion prediction method, is always transmitted. Thus, the hierarchical VBS motion estimation scheme can efficiently exploit the redundancies among neighboring motion vectors, providing an efficient motion vector encoding scheme. Also, a restricted search with respect to the topmost level motion vector enables more flexible and efficient motion estimation for the remaining lower level blocks. Computer simulations on the high resolution image sequence show that, the VBS motion estimation scheme provides a performance improvement of 0.6~0.7 dB, in terms of PSNR, compared to the fixed block size motion estimation scheme.