• Journal of Korean Neurosurgical Society
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• v.39 no.1
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• pp.26-31
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• 2006

Objective : The authors study on the clinical presentations and the surgical outcomes of the tumors in the ventricular system. Methods : 15 patients with ventricular tumor were studied. The clinical presentation, radiological findings, different surgical approaches, and outcome were analyzed. Tumors were classified into three groups based on their locations in MRI : lateral, third and fourth ventricle. Surgical methods were transcortical approach in eight patients, transcallosal approach in four, median suboccipital approach in two, and subfrontal approach in one. Gross total removal was achieved in 10 patients. Subtotal resections were performed in the rest. Glasgow outcome scale was used for evaluation of the surgical outcome. Results : Main clinical presentations were chronic headache in patients with the tumor in the lateral ventricular tumor and sudden onset of headache and consciousness change in patients with the tumor in the third and fourth ventricular tumor Development of hydrocephalus was more predominant in patients with the tumors in the third ventricle. Postoperatively, good outcome [Glasgow outcome scale IV, V] were in 73%, and better results was observed in patients with the tumors in the lateral ventricular tumor. The differences of outcome according to surgical approach were not recognized, even though it was not reliable statistically. Conclusion : In ventricular tumor, postoperative outcome is not good in patients with sudden development of headache, hydrocephalus, high grade tumor. Outcome is good in patients with the tumor in the lateral ventricle relatively. There is no difference in outcome according to the approach method to the tumors. And it is necessary to be aware of various approach methods to the tumors and anatomy surrounding the ventricle for avoidance of neurological complications.

• Journal of Chest Surgery
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• v.17 no.2
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• pp.257-262
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• 1984

Acute purulent pericarditis, though not common in incidence after introduction of antibiotics, is still potentially life treating isease. Since 1971, we have experienced 14 cases of acute purulent pericarditis with successful treatment. Among these 14 cases, 9 cases were male and they had high occurrence on their third to fifth decades in age distribution. Isolation of causative organisms were obtained in 11 cases through the bacterial culture of infectious source which was mainly pericardial effusion or blood, and the most frequently recovered organism was the staphylococcus aureus. Pre-existing inflammatory disease preceding to pericarditis, named as antecedent disease, were proved in 12 cases, and among which contiguous extension from the intrathoracic infection such as pneumonia or empyema accounted for the majority of antecedent disease. Pericardiocentesis with administration of antibiotics were tried in all cases, but result in recovery in 1 patient only. Remaining 13 cases had persistent picture of pericarditis and necessitated surgical drainage procedure. Ten of these 13 cases were underwent the open pericardial window using a mode of anterior approach in 4 and subxiphoid approach in 6 cases respectively. Two cases of subxiphoid group were reoperated by the anterior interphrenic pericardiectomy, due to insufficient drain of too thick effusion. In remaining 3 cases, anterior interphrenic pericardiectomy was performed initially because of purulent effusion already changed into fibrinopurulent peel with thickened pericardium. Through the experience of this series, we recommended that pericardiectomy should not be reluctant in purulent pericarditis as a initial surgical procedure for advantage of complete removal of infected space and avoidance of late constrictive pericarditis.

• Journal of Institute of Control, Robotics and Systems
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• v.7 no.9
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• pp.774-782
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• 2001

In this paper, we propose a new approach to the autonomous and high-speed indoor navigation of wheeled mobile robots using hybrid system controller. The hierarchical structure of hybrid system presented consists of high-level reasoning process and the low-level motion control process and the environmental interaction. In a discrete event system, the discrete states are defined by the user-defined constraints and the reference motion commands are specified in the abstracted motions. The hybrid control system applied for the nonholonomic mobile robots can combine the motion planning and autonomous navigation with obstacle avoidance in the indoor navigation problem. For the evaluation of the proposed algorithm, the algorithm is implemented to the two-wheel driven mobile robot system. The experimental results show that the hybrid system approach is an effective method for the autonomous navigation in indoor environments.

• Journal of the Korean Institute of Intelligent Systems
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• v.14 no.4
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• pp.457-467
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• 2004

In this paper, a robot is considered as an agent, a structure of robot is presented which consisted by multi-subagents and they have diverse capacity such as perception, intelligence, action etc., required for robot. Also, subagents are consisted by micro-agent($\mu$agent) charged for elementary action required. The structure of robot control have two sub-agents, the one is behavior based reactive controller and action selection sub agent, and action selection sub-agent select a action based on the high label action and high performance, and which have a learning mechanism based on the reinforcement learning. For presented robot structure, it is easy to give intelligence to each element of action and a new approach of multi robot control. Presented robot is simulated for two goals: chaotic exploration and obstacle avoidance, and fabricated by using 8bit microcontroller, and experimented.

• Korean Journal of Child Studies
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• v.35 no.4
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• pp.123-143
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• 2014

This research was based on achievement goal theory which categorizes young children's motivation into three types: mastery, the performance-approach, and performance-avoidance motivation. The participants consisted of forty-eight pairs of children aged 3-4 and their mothers. The participants completed two tasks in order to indentify their motivational types. The short form of the Child Behaviour Questionnaire(CBQ-SF), modified scales from Kim and Kim(2001), and the GIPEPS were also employed. The major findings of the research are as follows: First, in terms of the motivational types of the given sample, performance-approach motivation was ranked first followed by mastery motivation. Second, it was found that the temperament of young children was not related with their motivational types. Third, there were some differences in mother-child interaction between groups based on the frequency of feedback, questions, and the percentage of commands. Fourth, the mood of the relationship appeared to be the only factor of maternal interaction quality which related to children's mastery motivation.

• Journal of Institute of Control, Robotics and Systems
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• v.22 no.11
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• pp.904-911
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• 2016

This paper presents a novel driving system by the humanoid robot to drive a vehicle in disaster response situations. To enhance robot's capability for substituting human activities in responding to natural and man-made disaster, the one of prerequisite skills for the rescue robot is the mounted mobility to maneuver a vehicle safely in disaster site. Therefore, our driving system for the humanoid is developed in order to steer a vehicle through unknown obstacles even under poor communication conditions such as time-delay and black-out. Especially, the proposed system includes a tele-manipulation interface and stable navigation strategies. First, we propose a new type of path estimation method to overcome limited communication. Second, we establish navigation strategies when the operator cannot recognize obstacles based on Dynamic Window Approach. The effectiveness of the proposed developments is verified through simulation and experiments, which demonstrate suitable system for driving a vehicle in disaster response.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.6 no.1
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• pp.270-286
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• 2012

In this paper, we propose a novel routing protocol called the Cartography Enhanced OLSR (CE-OLSR) for multi hop mobile ad hoc networks (multi hop MANETs). CE-OLSR is based on an efficient cartography gathering scheme and a stability routing approach. The cartography gathering scheme is non intrusive and uses the exact OLSR reduced signaling traffic, but in a more elegant and efficient way to improve responsiveness to the network dynamics. This cartography is a much richer and accurate view than the mere network topology gathered and used by OLSR. The stability routing approach uses a reduced view of the collected cartography that only includes links not exceeding a certain distance threshold and do not cross obstacles. In urban environments, IEEE 802.11 radio signals undergo severe radio shadowing and fading effects and may be completely obstructed by obstacles such as buildings. Extensive simulations are conducted to study the performances of CE-OLSR and compare them with those of OLSR. We show that CE-OLSR greatly outperforms OLSR in delivering a high percentage of route validity, a much higher throughput and a much lower average delay. In particular the extremely low average delay exacerbated by CE-OLSR makes it a viable candidate for the transport of real time data traffic in multi hop MANETs.

• Asia-Pacific Journal of Business
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• v.14 no.3
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• pp.1-16
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• 2023

Purpose Despite the ongoing digital transformation, it is not clear whether emerging market firms follow their manufacturing FDI path in the emerging digital industries. This paper examines how digital orientation affects the location strategies in internationalization and how the existing innovation capacities moderate the link between digital orientation and the location strategies. Design/methodology/approach This study chooses the Chinese setting for research design because digital transformation is already prevalent in the society and the cases of outward expansion are salient among the emerging markets. It uses the panel dataset of 976 Chinese listed firms that consists of 6,648 observations spanning from 2007 to 2017. Ordinary least square regression is used for the statistical approach with a one-year lag in the model. Findings Digital orientation increases a likelihood of emerging multinationals' entries in developed countries, and a high level of innovative capacities strengthens the link. Two groups seem to prefer entries in developed countries: firms with a high level of digital orientation with a high level of innovative capacities and firms with a low level of digital orientation, if with a low level of innovative capacities. The former reflects the context of digital transformation and the latter hints at the tax avoidance or interests in real estate. Research implications or originality While emerging multinationals are known to prefer entries in developing countries for capacity arbitrage, our results forecast that their FDI strategies may have a drastic change as digital transformation deepens.

• The Journal of Korea Robotics Society
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• v.19 no.1
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• pp.117-129
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• 2024

This paper introduces collective navigation through a narrow gap using a curriculum-based deep reinforcement learning algorithm for a swarm of unmanned aerial vehicles (UAVs). Collective navigation in complex environments is essential for various applications such as search and rescue, environment monitoring and military tasks operations. Conventional methods, which are easily interpretable from an engineering perspective, divide the navigation tasks into mapping, planning, and control; however, they struggle with increased latency and unmodeled environmental factors. Recently, learning-based methods have addressed these problems by employing the end-to-end framework with neural networks. Nonetheless, most existing learning-based approaches face challenges in complex scenarios particularly for navigating through a narrow gap or when a leader or informed UAV is unavailable. Our approach uses the information of a certain number of nearest neighboring UAVs and incorporates a task-specific curriculum to reduce learning time and train a robust model. The effectiveness of the proposed algorithm is verified through an ablation study and quantitative metrics. Simulation results demonstrate that our approach outperforms existing methods.

• IEMEK Journal of Embedded Systems and Applications
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• v.12 no.5
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• pp.295-301
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• 2017

Recently, autonomous navigation technology, obstacle recognition, and obstacle collision avoidance technology are actively being developed for an unmanned surface vehicle (USV). The path to move from the current location to the destination should be planned, in order for an USV to autonomously operate safely to its destination. The dynamic window approach (DWA) is a well-known navigation scheme as a local path planning. The DWA algorithm derives the linear velocity and angular velocity by evaluating the destination direction, velocity, and distance from the obstacle. However, because DWA algorithm does not consider tracking the path, when using only the DWA algorithm, the ship may navigate away from the path line after avoiding obstacles. In this paper, we propose an improved DWA algorithm that can follow path line. And we implemented the simulation and compared the existing DWA algorithm with the improved DWA algorithm proposed in this paper. As a result, it is confirmed that the proposed DWA algorithm follows the path line better.