• The Journal of Korean Institute of Communications and Information Sciences
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• v.37A no.11
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• pp.979-985
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• 2012

The design of an efficient scheduler is a key design factor in IEEE 802.16m systems, in order to support services with various QoS smoothly. Although conventional studies of schedules have been suggested, those had problems that are not able to satisfy the delay condition and make the through-put declined, because they only focused on a specific action scenario rather than reflecting practical action scenarios which have real-time and non-real-time traffics variously. In this paper, an efficient uplink scheduling algorithm is proposed for IEEE 802.16m system by introducing the concepts of Virtual Time(VT) and Virtual Finish Time(VFT) based priority determination, and separate buffers for each QoS class in the mobile terminal. Simulation results showed that the proposed scheme had satisfied the delay requirement of real-time services even with improved throughput performance compared to conventional methods.

• Korean Journal of Computational Design and Engineering
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• v.12 no.2
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• pp.137-145
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• 2007

This paper concerns about residential environment analysis program implementation for design and analysis on public housing complexes such that view and daylight analysis processes are automated and integrated into existing design routine to achieve better design efficiency. Considering the architectural design trends this paper chooses ArchiCAD as a platform for a CAD system, which contains the concepts such as integrated object-oriented CAD, virtual building and BIM. Residential environment analysis system consists of three components. The first component is the 3D modeling part defining 3D form information for external geographic contour models, site models and interior/exterior of apartment buildings. The second is the parametric library part handling the design parameters for view and daylight analysis. The last is the user interface for the input/output and integration of data for the environment analysis. Daylight analysis shows rendered images as well as results of daylight reports and grades per time and performs the calculations for floor shadow. It separates the site-only analysis from the analysis of site and exterior environmental parameters. View analysis considers horizontal and vertical view angles to produce view image from each unit and uses the bitmap analysis method to determine opening ratio, scenery ratio and void ratio. We could expect better performance and precision from this residential environment analysis system than the existing 2D drawing based view and daylight analysis methods and overcome the existing one-way flow of design information from 3D form to analysis reports so that site design modifications are automatically reflected on analysis results. Each part is developed in a module so that further integration and extension into other related estimation and construction management systems are made possible.

• The Journal of Society for e-Business Studies
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• v.12 no.4
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• pp.185-209
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• 2007

The development of information technologies has contributed on-line training as one of important education methods. On-line training in firms, which is similar to e-learning or virtual education, provides trainees with more education opportunities in diverse ways. It has developed a range of innovative services with a one-stop solution of education within the electronic sector. Also under the on-line training environment, trainees can undertake customized training packages at anytime and any places. Moreover, information technology allows both the trainers and other trainees to be decoupled in any of the elements of tune, place, and space. Two research questions are investigated : what are the determinants affecting the on-line training effectiveness and how those variables affect the two aspects of training effectiveness: learning performance and transfer performance. Based on the previous literature conducted on the traditional training environment, the determinants of training effectiveness are derived. Eight hypotheses are developed based on literature reviews and tested by questionnaires survey data. The collected data have been analyzed by LISREL. It is found that the relationship between individual, organizational and on-line site design variables and training effectiveness (learning and transfer) are significant. The contribution and limitations of this research are also discussed with future studies.

• The korean journal of orthodontics
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• v.50 no.5
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• pp.293-303
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• 2020

Objective: To investigate the three-dimensional (3D) surgical accuracy between virtually planned and actual surgical movements (SM) of the maxilla in two-jaw orthognathic surgery. Methods: The sample consisted of 15 skeletal Class III patients who underwent two-jaw orthognathic surgery performed by a single surgeon using a virtual surgical simulation (VSS) software. The 3D cone-beam computed tomography (CBCT) images were obtained before (T0) and after surgery (T1). After merging the dental cast image onto the T0 CBCT image, VSS was performed. SM were classified into midline correction (anterior and posterior), advancement, setback, anterior elongation, and impaction (total and posterior). The landmarks were the midpoint between the central incisors, the mesiobuccal cusp tip (MBCT) of both first molars, and the midpoint of the two MBCTs. The amount and direction of SM by VSS and actual surgery were measured using 3D coordinates of the landmarks. Discrepancies less than 1 mm between VSS and T1 landmarks indicated a precise outcome. The surgical achievement percentage (SAP, [amount of movement in actual surgery/amount of movement in VSS] × 100) (%) and precision percentage (PP, [number of patients with precise outcome/number of total patients] × 100) (%) were compared among SM types using Fisher's exact and Kruskal-Wallis tests. Results: Overall mean discrepancy between VSS and actual surgery, SAP, and PP were 0.13 mm, 89.9%, and 68.3%, respectively. There was no significant difference in the SAP and PP values among the seven SM types (all p > 0.05). Conclusions: VSS could be considered as an effective tool for increasing surgical accuracy.

• Journal of the Korea Convergence Society
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• v.8 no.5
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• pp.19-28
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• 2017

In this paper, we propose a method to reduce the difference in image characteristics when multiple camera images are captured for virtual space production. Sixty-four images were used by cross-mounting eight bodies and lenses, respectively. Image analysis compares and analyzes the standard deviation of the histogram and pixel distribution values. As a result of the analysis, it shows different image characteristics depending on the lens or image sensor, though it is a camera of the same model. In this paper, we have adjusted the distribution of the overall brightness value of the image to compensate for this difference. As a result, the average deviation was the maximum of (Indoor: 6.89, outdoor: 24.23), we obtained images with almost no deviation (Indoor: maximum 0.42, outdoor: maximum: 2.73). In the future, we will study and apply more accurate image analysis methods than image brightness distribution.

• IEMEK Journal of Embedded Systems and Applications
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• v.4 no.4
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• pp.180-189
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• 2009

Currently, most automobile companies are interested in research on intelligent autonomous vehicle. They are mainly focused on driver's intelligent assistant and driver replacement. In order to develop an autonomous vehicle, lateral and longitudinal control is necessary. This paper presents a lateral and longitudinal control system for autonomous vehicle that has only mono-vision camera. For lane detection, we present a new lane detection algorithm using clothoid parabolic road model. The proposed algorithm in compared with three other methods such as virtual line method, gradient method and hough transform method, in terms of lane detection ratio. For adaptive control, we apply a vanishing point estimation to fuzzy control. In order to improve handling and stability of the vehicle, the modeling errors between steering angle and predicted vanishing point are controlled to be minimized. So, we established a fuzzy rule of membership functions of inputs (vanishing point and differential vanishing point) and output (steering angle). For simulation, we developed 1/8 size robot (equipped with mono-vision system) of the actual vehicle and tested it in the athletics track of 400 meter. Through the test, we prove that our proposed method outperforms 98 % in terms of detection rate in normal condition. Compared with virtual line method, gradient method and hough transform method, our method also has good performance in the case of clear, fog and rain weather.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.32 no.6A
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• pp.411-418
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• 2012

In this study, behavior of unpatched and patched cylindrical shells with through-wall cracks has been estimated using numerical experiments, and patching effect of them has been investigated according to various patching parameters. To show credibility of numerical models considered, two ways such as h- and p-methods have been adopted. Also, domain integral method and virtual crack extension method have been considered to calculate energy release rates based on linear elastic fracture mechanics. For examples, the unpatched cylindrical shells with circumferential cracks under remote tension have firstly been analyzed to show the validity of finite element modeling with h-method or p-method, and then the results have been compared with literature values published. Next, the sensitive analysis of patch repaired problems in terms of thickness of patch and adhesive, shear modulus of adhesive, composite material type of patch, crack length, etc. has been carried out.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.35 no.5
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• pp.459-467
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• 2011

Rehabilitation exercises must maintain a patient's interest and permit a quantitative evaluation of the rehabilitation. We have developed a haptic-device system. When users move a grip, the haptic device provides a virtual force that either assists the movement of their arm or working against it. To investigate the functional effect of this system in a rehabilitation program, we used for five subjects with motor-function disorders and measured the grip position, velocity, force exerted on the grip, and EMG activities during a reaching task of one subject. The accuracy of the grip position, velocity and trajectories patterns were similar for all the subjects. The results suggested that the EMG activities were improved by applying the virtual force to the grip. These results can be used for the development of rehabilitation programs and evaluation methods.

• International Journal of Highway Engineering
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• v.14 no.5
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• pp.165-177
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• 2012

PURPOSES: The number of traffic accidents in 2010 was 226,978 in Korea, a high percentage of which up to 12.61% was due to drunk driving. As it is expected that the number of traffic accidents will increase because of the drastic increase of the number of vehicle registrations and the prevalent drinking cultures, it is necessary to understand the driving characteristics of drunken drivers to lower the increasing rate. METHODS: This study, therefore, comparatively analyzes the two groups - one group before drinking and the other after drinking - based on the graph, and implements the correlation in each scenario(1,2,3). scenario 1. appearance of jaywalkers; scenario 2. appearance of an illegal left-turning car; and scenario 3. appearance of a vehicle and a person as obstacles to the driver after an accident. RESULTS: The comparative analysis of speed shows that the group after drinking was 50km/h faster than the group before drinking in Scenario 1, 20km/h in Scenario 2, and 15km/h in Scenario 3 respectively. In the comparative analysis of acceleration, the average level of the group after drinking was 0.15 higher than that of the group before drinking in Scenario 1, 0.30 in Scenario 2, and 0.15 in Scenario 3. In the comparative analysis of deceleration, the average level of the group after drinking was about 0.4 lower than that of the group before drinking in Scenario 1, 0.35 in Scenario 2, and 0.2 in Scenario 3 respectively. In the comparative analyses, the item of speed, acceleration and deceleration was of significance for each group in Scenarios. CONCLUSIONS: The comparative analysis demonstrated that there is a difference between the group before drinking and the group after drinking. In the analysis of correlation in each group, it was proved that the drunken group was of significance.

• International Journal of Highway Engineering
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• v.19 no.5
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• pp.163-171
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• 2017

PURPOSES : Traffic safety facilities are used to prevent traffic accidents before they occur by providing drivers with information on traffic situations and the geometric design of roads. However, some facilities not defined in guidelines do not meet installation criteria, yet are being installed and used in order to increase efficiency in traffic flow and prevent traffic accidents in a specific expressway zone. In this study, we have evaluated the effect of delineation system which are not defined in the guideline criteria. METHODS : Different virtual scenarios were created for roads using expressway median barrier chevron signs, with a driving simulator used to evaluate the installation and operational effect of such signs. Ten experiments were performed with left- and right-curved roads at curve radius intervals of 500 m, from 500 m to 2,500 m. RESULTS : For sections with a curve radius of more than 1,500 m, drivers had a clear tendency toward stable driving regardless of delineation system. When a chevron sign is installed on a protection fence in the road curving left, an expanded installation is recommended up to the section with a curve radius of 1,000 m. According to the analysis results for the RHB (Relative High Beta spectrum), driving concentration also improved up to a curve radius of 1,000 m. CONCLUSIONS :The experiment result indicates the extent of biasing within a lane and the manipulation amount of steering handle, were analyzed and found to be affected by curve radius and road alignment regardless of delineation system.