• KSII Transactions on Internet and Information Systems (TIIS)
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• v.14 no.4
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• pp.1738-1756
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• 2020

To improve the accuracy and realism of the virtual surgical simulation system, this paper proposes an optimized mass-spring model with shape restoration ability based on volume conservation to simulate soft tissue deformation. The proposed method constructs a soft tissue surface model that adopts a new flexion spring for resisting bending and incorporates it into the mass-spring model (MSM) to restore the original shape. Then, we employ the particle swarm optimization algorithm to achieve the optimal solution of the model parameters. Besides, the volume conservation constraint is applied to the position-based dynamics (PBD) approach to maintain the volume of the deformable object for constructing the soft tissue volumetric model base on tetrahedrons. Finally, we built a simulation system on the PHANTOM OMNI force tactile interaction device to realize the deformation simulation of the virtual liver. Experimental results show that the proposed model has a good shape restoration ability and incompressibility, which can enhance the deformation accuracy and interactive realism.

• PNF and Movement
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• v.15 no.3
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• pp.227-236
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• 2017

Purpose: The purpose of this study was to investigate the effects of coordinative locomotor training (CLT) on the foot pressure and balance of patients with scoliosis. Methods: This was a single-case A-B-A study involving two patients with scoliosis. The study was designed to perform repeated measurements as follows: 5 times at baseline (A), 10 times during intervention (B), and 5 times after intervention (A). The study period was 5 weeks, and the CLT program was divided into warm up, CLT program, and cool down stages, at 50 min per stage. For the primary outcome measure, Gait View AFA-50 was used to determine the foot pressure and balance ability. For the secondary outcome measure, the SRS-22 questionnaire was used to assess the quality of life of the patients with scoliosis. Descriptive statistics and visual analysis using graphs were used to compare the rates of change. Results: The results of this study showed that the foot pressure and balance ability of the two subjects improved during the intervention period and remained improved even during the baseline period. However, their quality of life did not change after the intervention. Conclusion: CLT may have a positive effect on foot pressure and balance ability in patients with scoliosis. Also, this body function improvement may have positive effects on the performance of daily activities which employ the upright position.

• Management & Information Systems Review
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• v.36 no.1
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• pp.233-249
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• 2017

This study investigates the relation of managerial ability and firm performance in case of Chaebol in Korea. We employ non-financing firms at Korean markets for the period 2000-2015. Most important decision is made by the head of Chaebol which increases firm value eventually and he has such a strong dominant power that managers belongs to Chaebol have to follow mother firm's decision directions. So it is expected that managers belongs to Chaebol have to focus on long term performance rather than short term profits, which means they concentrate their managerial ability much on the firm value. Otherwise, managers in which non-Chaebol focus their ability on periodic accounting earnings. Thus, this study examines an empirical analysis on the relation of managerial ability and firm performance and the effect of Chaebol on the relation of managerial ability and firm performance. Empirical results are as follows: First, there exists a statistically significant positive relation between managerial ability and firm performance either short- or long-term. Second, we extend this relationship into Chaebol condition and find that managerial ability of Chaebol positively influences on the firm value which is long-term performance, rather than return on assets which is short-term performance. These results imply that managers belongs to Chaebol much concentrate their ability on long-term value which is differenciated from the case of non-Chaebol samples. Chaebol is an important issue in Korea because it dominates most of Korean local economy so its' impact from small changes on our economy is big enough. Our study examining the relationships between managerial ability of Chaebol and firm performance is meaningful and it is a good signal that they concentrate their ability much on the long-term value rather than short-term profits. We expect that the results of this study will provide the academic and practical references. This study will contribute to the future research in accounting through an analysis of managerial ability which is a new measure, Chaebol, and firm value.

• International Area Studies Review
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• v.16 no.3
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• pp.53-73
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• 2012

In this study we investigate the ability of the yield spread to predict economic recessions in two Asian economies. For our purpose we use the data from two emerging economies (South Korea and Thailand) that are also known for their openness in terms of exports and imports. We employ both two-regime Markov-Switching model (MS) and three-regime MS model to estimate the probability of recessions during Asian crisis. We found that the yield spread is confirmed to be a reliable recession predictor for Thailand but not for South Korea. The three-regime MS model is better for capturing the Asian financial crisis than two-regime MS model. We also tried to find the duration of economic expansions and recessions. We tested the hypothesis of asymmetric movements of business cycles. The MS results are also compared with that of the standard probit model for comparison. The MS model does not significantly improve the forecasting ability of the yield spread in forecasting business cycles.

• Journal of the Korean Geosynthetics Society
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• v.6 no.3
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• pp.25-30
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• 2007

The major reason to employ electrokinetic geosynthetics is to take advantage of its ability to densify very low permeability materials in shorter time periods than ordinary seepage consolidation. A number of laboratory scale experiments was carried out with acrylic column using natural clayey soil. The testing results indicate that (1) the electrically induced settlement was faster than the gravitational one, (2) the higher the voltage, the faster the dewatering but the less final settlement, and (3) the pH extended as low as 3 in the anode section and as high as 11 near the cathode.

• Journal of the Korean Society for Nondestructive Testing
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• v.28 no.6
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• pp.531-537
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• 2008

One of the fundamental features of time reversal acoustic (TRA) techniques is the ability to focus the propagating ultrasonic beam to a specific point within the test material. Therefore, it is important to understand the focusing properties of a TR device in many applications including nondestructive testing. In this paper, we employ an analytical scheme for the analysis of TR beam focusing in a homogeneous medium. More specifically, a nonparaxial multi-Gaussian beam (NMGB) model is used to simulate the focusing behavior of array transducers composed of multiple rectangular elements. The NMGB model is found to generate accurate beam fields beyond the nonparaxial region. Two different simulation cases are considered here for the focal points specified on and off from the central axis of the array transducer. The simulation results show that the focal spot size increases with increasing focal length and focal angle. Furthermore, the maximum velocity amplitude does not always coincide with the specified focal point. Simulation results for the off-axis focusing cases do demonstrate the accurate steering capability of the TR focusing.

• Journal of the Korean Society for Nondestructive Testing
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• v.30 no.6
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• pp.569-577
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• 2010

Nonplanar surface geometries of components are frequently encountered in real ultrasonic inspection situations. Use of rigid array transducers can lead to beam defocusing and reduction of defect image quality due to the mismatch between the planar array and the changing surface. When a flexible array is used to fit the complex surface profile, the locations of array elements should be known to compute the delay time necessary for adaptive heam focusing. An alternative method is to employ the time reversal focusing technique that does not require a prior knowledge about the properties and structures of the specimen and the transducer. In this paper, a time reversal method is applied to simulate beam focusing of flexible arrays and imaging of point-like defects contained in specimens with nonplanar surface geometry. Quantitative comparisons are made for the performance of a number of array techniques in terms of the ability to focus and image three point-like reflectors positioned at regular intervals. The sinusoidal profile array studied here exhibits almost the same image quality as the flat, reference case.

• English Language & Literature Teaching
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• v.16 no.4
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• pp.71-90
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• 2010

This study suggests that English literature educators need to be eclectic and flexible in applying theories and methods, not simply adhering to one or two for all situations and occasions. They need to be available to go with the flow and particularly employ whatever is needed at any given moment of class time. There is a current trend emphasizing English literature as merely a language resource rather than the study of English literature as an end in itself. Without much attention given to literary analysis and criticism, students tend to lack creative and critical thinking abilities. Given the current imbalance, it would seem important to address the issue, and create English class programs that maintain a balance between teaching the study of English literature to improve students' critical thinking abilities, and its use as a language resource. To fulfill this goal, thorough preparation is required. Indeed, we can direct our intelligence more effectively when we are well prepared and we are familiar with the basic methods and mechanics of teaching our subject. The greatest achievement of the English literature class I taught was that the students showed unexpectedly remarkable creative and critical appreciation of the novel we studied, in addition to improving their English language skills.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.11 no.2
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• pp.959-981
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• 2017

Existing Android malware detection approaches mostly have concentrated on superficial features such as requested or used permissions, which can't reflect the essential differences between benign apps and malware. In this paper, we propose a quantitative calculation model of application risks based on the key observation that the essential differences between benign apps and malware actually lie in the way how permissions are used, or rather the way how their corresponding permission methods are used. Specifically, we employ a fine-grained analysis on Android application risks. We firstly classify application risks into five specific categories and then introduce comprehensive risk, which is computed based on the former five, to describe the overall risk of an application. Given that users' risk preference and risk-bearing ability are naturally fuzzy, we design and implement a fuzzy logic system to calculate the comprehensive risk. On the basis of the quantitative calculation model, we propose a risk classification based approach for Android malware detection. The experiments show that our approach can achieve high accuracy with a low false positive rate using the RandomForest algorithm.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.52 no.4
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• pp.212-222
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• 2003

The ability to efficiently and robustly recover accurate 3D terrain models from sets of stereoscopic images is important to many civilian and military applications. A stereo matching has been an important tool for reconstructing three dimensional terrain. However, there exist many factors causing stereo matching error, such as occlusion, no feature or repetitive pattern in the correlation window, intensity variation, etc. Among them, occlusion can be only resolved by true multi-image stereo. In this paper, we present multi-image stereo method using DEM fusion as one of efficient and reliable true multi-image methods. Elevations generated by all pairs of images are combined by the fusion process which accepts an accurate elevation and rejects an outlier. We propose three fusion schemes: THD(Thresholding), BPS(Best Pair Selection) and MS(Median Selection). THD averages elevations after rejecting outliers by thresholding, while BPS selects the most reliable elevation. To determine the reliability of a elevation or detect the outlier, we employ the measure of self-consistency. The last scheme, MS, selects the median value of elevations. We test the effectiveness of the proposed methods with a quantitative analysis using simulated images. Experimental results indicate that all three fusion schemes showed much better improvement over the conventional binocular stereo in natural terrain of 29 Palms and urban site of Avenches.