• Journal of Korean Society for Atmospheric Environment
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• v.23 no.E2
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• pp.66-73
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• 2007

The introduction of tracer gas techniques to ventilation studies in indoor environments provides valuable information that used to be unattainable from conventional testing environments. Data acquisition systems (DASs) containing analogue-to-digital (A/D) converters are usually used to function the key role that records signals to storage in digital format. In the testing process, there exist a number of components in the measuring equipment which may produce system-based inference to the monitored results. These unwanted fluctuations may cause significant error in data analysis, especially when non-linear algorithms are involved. In this study, a pre-processor is developed and applied to separate the unwanted fluctuations (noise or interference) in raw measurements and to reduce the uncertainty in the measurement. Moving average, notch filter, FIR (Finite Impulse Response) filters, and IIR (Infinite Impulse Response) filters are designed and applied to collect the desired information from the raw measurements. Tracer gas concentrations are monitored during leakage and ventilation tests in the model test room. The signal analysis functions are introduced to carry out the digital signal processing (DSP) work. Overall the FIR filters process the $CO_2$ measurement properly for ventilation rate and mean age of air calculations. It is found that, the Kaiser filter was the most applicable digital filter for pre-processing the tracer gas measurements. Although the IIR filters help to reduce the random noise in the data, they cause considerable changes to the filtered data, which is not desirable.

• Water Engineering Research
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• v.5 no.3
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• pp.111-121
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• 2004

For the long-term strategic water resources planning, forecasting the future streamflow change is important to meet the demand of a growing society. The streamflow variation to the decade-long precipitation was investigated for the two major stage gauging stations in Korea. Precipitation and runoff characteristics have been analyzed at Yongwol stream stage in the Han River as well as Sutong stream stage in the Kum River for the future water resources management strategies. Monte Carlo method has been applied to estimate the future precipitation and runoff. Based on the trend line of 10-year moving average of runoff depth for the historical runoff records, the relation between runoff and the time variation was examined in more detail using regression analysis. This study showed that the surface flows have been significantly decreased while precipitation has been stable in these basins. Decreasing in runoff reflects the regional watershed characteristics such as forest cover changes. The findings of this study could contribute to the planning and development for the efficient water resources utilization.

• Journal of Korean Neurosurgical Society
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• v.57 no.3
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• pp.178-184
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• 2015

Objective : Posterior vertebral translation as a type of spondylolisthesis, retrolisthesis is observed commonly in patients with degenerative spinal problems. Nevertheless, there is insufficient literature on retrolisthesis compared to anterolisthesis. The purpose of this study is to clarify the clinical features of retrolisthesis, and its developmental mechanism associated with a compensatory role in sagittal imbalance of the lumbar spine. Methods : From 2003 to 2012, 230 Korean patients who underwent spinal surgery in our department under the impression of degenerative lumbar spinal disease were enrolled. All participants were divided into four groups : 35 patients with retrolisthesis (group R), 32 patients with simultaneous retrolisthesis and anterolisthesis (group R+A), 76 patients with anterolisthesis (group A), and 87 patients with non-translation (group N). The clinical features and the sagittal parameters related to retrolisthesis were retrospectively analyzed based on the patients' medical records. Results : There were different clinical features and developmental mechanisms between retrolisthesis and anterolisthesis. The location of retrolisthesis was affected by the presence of simultaneous anterolisthesis, even though it predominantly manifest in L3. The relative lower pelvic incidence, pelvic tilt, and lumbar lordosis compared to anterolisthesis were related to the generation of retrolisthesis, with the opposite observations of patients with anterolisthesis. Conclusion : Retrolisthesis acts as a compensatory mechanism for moving the gravity axis posteriorly for sagittal imbalance in the lumbar spine under low pelvic incidence and insufficient intra-spinal compensation.

• Journal of the Korean Society of Propulsion Engineers
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• v.12 no.3
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• pp.68-75
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• 2008

The three-dimensional structure of detonation wave propagating in a circular tube was investigated using a parallel computational code developed previously. A series of parametric study for a circular tube of a fixed diameter gave the formation mechanism of the detonation cell structures depending on pre-exponential factor, k. The unsteady results in three-dimension showed the mechanisms of two, three and four cell mode of detonation wave front structures. The detonation cell number was increased but cell width and length were decreased with increased pre-exponential factor k. In the all multi-cell mode, the detonation wave structure and smoked-foil records on the wall are made by the moving of transverse waves. The detonation wave front structures have the regular polygon and windmill shapes periodically.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.9 no.5
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• pp.1717-1732
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• 2015

The widespread use of location-based services (LBSs), which allows untrusted service provider to collect large number of user request records, leads to serious privacy concerns. In response to these issues, a number of LBS privacy protection mechanisms (LPPMs) have been recently proposed. However, the evaluation of these LPPMs usually disregards the background knowledge that the adversary may possess about users' contextual information, which runs the risk of wrongly evaluating users' query privacy. In this paper, we address these issues by proposing a generic formal quantification framework,which comprehensively contemplate the various elements that influence the query privacy of users and explicitly states the knowledge that an adversary might have in the context of query privacy. Moreover, a way to model the adversary's attack on query privacy is proposed, which allows us to show the insufficiency of the existing query privacy metrics, e.g., k-anonymity. Thus we propose two new metrics: entropy anonymity and mutual information anonymity. Lastly, we run a set of experiments on datasets generated by network based generator of moving objects proposed by Thomas Brinkhoff. The results show the effectiveness and efficient of our framework to measure the LPPM.

• Annual Conference on Human and Language Technology
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• 1991.10a
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• pp.196-208
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• 1991

This study focused on the role of prefabricated speech (routines and patterns) in the L2 acquisition process. The data for this study consisted of spontaneous speech samples and various observational records of three Korean children learning English as L2 in a nursery school. The specific questions addressed here were: (1) What routines, patterns, and creative constructions did the children use? (2) What was the general trend in the three children's use of routines, patterns, and creative constructions over time? The data were collected over a period of one school year by observing the children in their school. The findings were discussed from the perspective of human information processing. This study found that prefabricated speech played a significant role in the three children's L2 acquisition. The automatic processing of prefabricated speech appeared to enable the children to reduce the burden on their information processing systems, which allowed the saved resources available for other language development activities. Also, the children's language development was evident in their increase in the use of patterns. The children were moving from heavy dependence on wholly unanalyzed routines to increased use of partly unanalyzed patterns. This increased control was the result of an increase in procedural knowledge.

• Korean Institute of Interior Design Journal
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• v.19 no.1
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• pp.75-84
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• 2010

This study will establish the transformal characteristics of architectural visual information by investigating: how contemporary architects perceive and process multifaceted architectural information via the expression media since 1970s. The purposes and results of this study are summarized as follows: This study established the contemporary transformal characteristics by comparing the expression methods of traditional architects with the transformal characteristics of visual information derived from the contemporary architectural expression media. In a pluralistic information society, the expression methods of the past, which recognize space as a stationary, unidimensional visual point on a drawing surface, is now changing to the mixed, multidimensional expression methods that connect various visual points on a limited drawing surface. Furthermore, the rapid advancement of digital media is changing, from a method which simply arranges visual information, to a flexible visual tool which can process architecture sequentially and simultaneously. As the communication structure of architecture is moving toward an individual-centered two-way communication type, the information delivery method is used to visualize conceptual, inferential information, rather than visualizing realistic information which simply records facts. In the past, multidimensional, non-linear forms could not be processed by the conventional design processes and sketch work, but now they can be expressed via digital media.

• Journal of Electrical Engineering and Technology
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• v.13 no.3
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• pp.1089-1098
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• 2018

This study aims at developing and applying a hybrid model to the wind power prediction (WPP). The hybrid model for a very-short-term WPP (VSTWPP) is achieved through analytical data, multiple linear regressions and least square methods (MLR&LS). The data used in our hybrid model are based on the historical records of wind power from an offshore region. In this model, the WPP is achieved in four steps: 1) transforming historical data into ratios; 2) predicting the wind power using the ratios; 3) predicting rectification ratios by the total wind power; 4) predicting the wind power using the proposed rectification method. The proposed method includes one-step and multi-step predictions. The WPP is tested by applying different models, such as the autoregressive moving average (ARMA), support vector machine (SVM), and artificial neural network (ANN). The results of all these models confirmed the validity of the proposed hybrid model in terms of error as well as its effectiveness. Furthermore, forecasting errors are compared to depict a highly variable WPP, and the correlations between the actual and predicted wind powers are shown. Simulations are carried out to definitely prove the feasibility and excellent performance of the proposed method for the VSTWPP versus that of the SVM, ANN and ARMA models.

• Journal of architectural history
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• v.28 no.2
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• pp.19-30
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• 2019

The former administration office building of Kyeong-seong-bu(京城府) was a building converted from the Japanese residency-general's of Kyeong-seong(京城理事廳) which was originally built as the Japanese consulate in Joseon(日本領事館). It was too worn and too small as a Kyeong-seong-bu administration office even with several annexes. Kyeong-seong-bu tried to build a new big administration office building at the vacant north side of the same site, which was closely faced to the rotary in front of the Bank of Joseon(朝鮮銀行前廣場). But this trial was ended in vain due to insufficient budget. Therefore Kyeong-seong-bu built a new administration office building in another site and moved to it in 1926 with debts. For paying for the debts Kyeong-seong-bu sold the former site after partitioning with new roads through it. As a result the nature of the former site and its surroundings was changed. This study traces the changes and inquires how the authorities in the colonial Joseon and various commercial powers of Kyeong-seong-bu behaved for their own interests in the meantime. It makes use of the historical records and documentary literatures between early 1910s and early 1930s.

• Structural Engineering and Mechanics
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• v.77 no.5
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• pp.613-626
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• 2021

In this paper, an enhanced Violation-based Sensitivity analysis and Border-Line Adaptive Sliding Technique (ViS-BLAST) will be utilized for optimization of some well-known structural and mechanical engineering problems. ViS-BLAST has already been introduced by the authors for solving truss optimization problems. For those problems, this method showed a satisfactory enactment both in speed and efficiency. The Enriched ViS-BLAST or EVB is introduced to be vastly applicable to any solvable constrained optimization problem without any specific initialization. It uses one-directional step-wise searching technique and mostly limits exploration to the vicinity of FNF border and does not explore the entire design space. It first enters the feasible region very quickly and keeps the feasibility of solutions. For doing this important, EVB groups variables for specifying the desired searching directions in order to moving toward best solutions out or inside feasible domains. EVB was employed for solving seven numerical engineering design problems. Results show that for problems with tiny or even complex feasible regions with a larger number of highly non-linear constraints, EVB has a better performance compared to some records in the literature. This dominance was evaluated in terms of the feasibility of solutions, the quality of optimum objective values found and the total number of function evaluations performed.