• Journal of Korean Neurosurgical Society
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• v.63 no.2
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• pp.237-247
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• 2020

Objective : Fixation of the C1-2 segment is challenging because of the complex anatomy in the region and the need for a high degree of accuracy to avoid complications. Preoperative 3D-computed tomography (CT) scans can help reduce the risk of complications in the vertebral artery, spinal cord, and nerve roots. However, the patient may be susceptible to injury if the patient's anatomy does not match the preoperative CT scans. The intraoperative 3D image-based navigation systems have reduced complications in instrument-assisted techniques due to greater accuracy. This study aimed to compare the radiologic outcomes of C1-2 fusion surgery between intraoperative CT image-guided operation and fluoroscopy-guided operation. Methods : We retrospectively reviewed the radiologic images of 34 patients who underwent C1-2 fusion spine surgery from January 2009 to November 2018 at our hospital. We assessed 17 cases each of degenerative cervical disease and trauma in a study population of 18 males and 16 females. The mean age was 54.8 years. A total of 139 screws were used and the surgical procedures included 68 screws in the C1 lateral mass, 58 screws in C2 pedicle, nine screws in C2 lamina and C2 pars screws, four lateral mass screws in sub-axial level. Of the 34 patients, 19 patients underwent screw insertion using intraoperative mobile CT. Other patients underwent atlantoaxial fusion with a standard fluoroscopy-guided device. Results : A total of 139 screws were correctly positioned. We analyzed the positions of 135 screws except for the four screws that performed the lateral mass screws in C3 vertebra. Minor screw penetration was observed in seven cases (5.2%), and major pedicle screw penetration was observed in three cases (2.2%). In one case, the malposition of a C2 pedicle screw was confirmed, which was subsequently corrected. There were no complications regarding vertebral artery injury or onset of new neurologic deficits. The screw malposition rate was lower (5.3%) in patients who underwent intraoperative CT-based navigation than that for fluoroscopy-guided cases (10.2%). And we confirmed that the operation time can be significantly reduced by surgery using intraoperative O-arm device. Conclusion : Spinal navigation using intraoperative cone-beam CT scans is reliable for posterior fixation in unstable C1-2 pathologies and can be reduced the operative time.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.38 no.5
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• pp.497-503
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• 2014

Minimally invasive intramedullary nail insertion or plate osteosynthesis has shown good results for the treatment of long bone fractures. However, directly seeing the fracture site is impossible; surgeons can only confirm bone fragments through a fluoroscopic imaging system. The narrow field of view of the equipment causes malalignment of the fracture reduction, and radiation exposure to medical staff is inevitable. This paper suggests two methods to solve these problems: surgical navigation using 3D models reconstructed from computed tomography (CT) images to show the real positions of bone fragments and estimating the rotational angle of proximal bone fragments from 2D fluoroscopic images. The suggested methods were implemented using open-source code or software and evaluated using a model bone. The registration error was about 2 mm with surgical navigation, and the rotation estimation software could discern differences of $2.5^{\circ}$ within a range of $15^{\circ}$ through a comparison with the image of a normal bone.

• 한국HCI학회:학술대회논문집
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• 2008.02a
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• pp.510-516
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• 2008

In ubiquitous environment, there are no limits to utilize networks whenever and wherever you are. That pervasive networks are combined with the information devices and then create various services such as car navigation of LBS(location based service) and DMB(Digital Multimedia Broadcasting). As these kinds of services are getting more various, the complexity is also getting higher and ultimately the convergence will make people feel frustrated. One of the solutions is Context-Awareness[1] technology. User interface with context-awareness filters unnecessary information and prevents users from being blocked due to the massive information. In this paper, we describe the seamless service system based on location-awareness, which is a type of context-awareness. We developed the system based on UPnP AV Framework. This system provides the automatic terminal device selection for the nomadic user. The system establishes new connections for the ongoing streaming playback session with the new AV devices without substantial loss of playback so that the user can enjoy the seamless service. The AV device selection based on the user's location needs no user's intervention or notification so it achieves the improvement of usability and complexity.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.15 no.6
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• pp.1238-1244
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• 2011

This paper presents the matching method of reflectors for localization of laser navigation. The laser navigation is a device that measures distance and angle of reflector. The conventional major matching using the laser navigation is method that moves position of measured reflectors to position of installed reflectors and than rotate moved reflectors. However, it is difficult to use the industry because it has high computational complexity and high errors. To solve those problem, The proposed matching is method that create position of measured reflectors to assume that the position of installed reflectors is position of AGV and than rotate the position of installed reflectors. For experiment, we used AGV which was designed by ourselves, and compared positioning accuracy when AGV moves according to varying steering angle and driving speed.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2017.11a
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• pp.220-221
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• 2017

The initial light emitting diode (LED) has been used as a display device for various mechanical devices due to its low power. The development of LED technology has made it possible to express color with high power and high brightness. Therefore, it is used as a display such as a traffic signal, a large electric signboard, and an automobile display, and is also adapted as an indoor or outdoor light source such as an incandescent or a fluorescent lamp which requires the high luminance. The bulb of marine lantern, which is used for the aids to navigation, was replaced to LED. The first marine LED lantern was manufactured using multiple LEDs. However, if the optical design is renewed by the development of LED or even if a few LEDs are used, it is possible to satisfy the brightness and the light distribution required by the marine LED lantern.

• Journal of the Korea Safety Management & Science
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• v.12 no.1
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• pp.113-118
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• 2010

"Domestic delivery service" is defined the service to deliver goods or packages from point of senders to point of receiver. With the characteristics of door to door, it is must a service provider should know the exact location of destination assuring best utilization of moving path. Generally, location information consist of postal code and address only, which result in difficulties to identify the precise location of destination. It is relatively less correlated between the information that address refers and practical location in Korea address system. For example, the next door to house number 100 is not always house number 101. Therefore, a delivery man additionally uses a paper map or a GPS navigation which carry extra job to input every code of location to the device in order to know precise location. It is also very inconvenient that every delivery man identify the location that address information refers and make a personal decision of the optimum moving path dropping each destination without calculating provisioning process of whole delivery path. As explained above, it is inefficient to find information delivery service required and to generate the optimum path. In results, these difficulties bring in delay of service and increase of cost. In this point, the contents of the thesis suggest a GPS navigation system easy to obtain accuracy of delivery information which enables to automate optimum moving path based on RFID which contains location information.

• Journal of Navigation and Port Research
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• v.38 no.3
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• pp.211-216
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• 2014

In this paper, high throughput method is studied to provide floating objects with broadband service as ship by using satellite. In recent, satellite broadcastings standard is based on DVB-S3 for communication service using wireless device on navigation communication by satellite. LDPC codes are iterative coding algorithm proposed in DVB-S3. In this paper, FTN technique is applied to LDPC codes with 8-PSK modulation and then present the method to alleviate performance degradation due to FTN through BICM-ID. BICM-ID is the method to improve performance by calculating a new LLR from hard-decision value of decoder output. DVB-S2 system with 8-PSK modulation and FTN technique based on iterative decoding had a better performance than DVB-S2 with 8-PSK modulation and FTN technique over Gaussian channels.

• Journal of the Korean Institute of Intelligent Systems
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• v.21 no.6
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• pp.692-697
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• 2011

There are many researches to develop robots that improve its mobility to adapt in various uneven environments. In the paper, a hybrid mobile robot that can dock with the other robot and transforms between wheeled robot and legged robot is proposed. The hybrid mobile robot platform has docking device with a peg and a cup module. In addition, the robot is possible to walk and drive according to condition of the road. A navigation algorithm of the hybrid mobile robot is proposed to improve the mobility of robots using docking algorithm based on image processing on the broken road and uneven terrain. The proposed method recognizes road condition through PSD sensor attached in front and bottom of the robot and selects an appropriate navigation method according to terrain surface. The proposed docking and navigation methods are verified through experiments using hybrid mobile robots.

• Journal of the Korean Institute of Intelligent Systems
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• v.16 no.5
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• pp.616-621
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• 2006

Recently many cars are equipping a navigation system. The main purpose of the early system guides a user through the route. A navigation system includes various abilities by development of various technologies and it has given more convenience to user. It can play various records on the tape and announces which are useful information about each road. Also it can use various multi-media contents by DMB device during driving. However, guide function of basic and important road in the navigation system has not grown greatly yet. In this paper, we proposed recommendation method of human-friendly road considering user's condition through various information of outside environment, user's velocity intention, a driver's emotion and a preference of the road. Modules consists of hierarchical structure that can easily correct and add each algorithm and those use fuzzy logic algorithm.

• Journal of the Korean Institute of Intelligent Systems
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• v.20 no.3
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• pp.311-317
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• 2010

In the paper, we propose an improved mobility method of modular robots by physical docking in the uneven environments. The modular robot system consists of autonomous docking device, 3 DOF robotic arm, motion controller, and main controller. Real-time location and direction of the robot are estimated using inner GPS and they are used to control direction and path of each robot for physical docking between modular robots. We design a navigation algorithm of modular robot using physical docking and cooperative navigation in the environment with broken road and low stair. The proposed method is verified by navigation experiments of three developed modular robots in the uneven environments.