• Journal of the Korea Institute of Information and Communication Engineering
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• v.10 no.2
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• pp.380-385
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• 2006

In this paper, a program that can be utilized to measure and analyze radio propagation characteristics is developed. This program is able to control the measurement instruments including spectrum analyzer through GPIB interface and analyze the measured data to yield mean excess delay and RMS delay spread. The measured path loss can be compared with theoretical value in free space or inside a tunnel. The measured and analyzed results can also be presented in the forms of graphs. As these tasks can be conducted on the spot of the measurements, this program is very helpful in performing and verifying the measurements immediately. In this thesis radio propagation characteristics with frequency bands of 2.45 and 5.8GHz in subway tunnels are measured by using the program. Path loss and delay spread in subway tunnel is measured and compared according to the form of antenna beam and LOS(Line of Sight) and N-LOS(Non-Line of Sight).

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• v.2
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• pp.15-22
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• 2006

This paper presents a novel signal tracking algorithm for GNSS receivers using a MLE technique. In order to perform a robust signal tracking in severe signal environments, e.g., high dynamics for navigation vehicles or weak signals for indoor positioning, the MLE based signal tracking approach is adopted in the paper. With assuming white Gaussian additive noise, the cost function of MLE is expanded to the cost function of NLSE. Efficient and practical approach for Doppler frequency tracking by the MLE is derived based on the assumption of code-free signals, i.e., the cost function of the MLE for carrier Doppler tracking is used to derive a discriminator function to create error signals from incoming and reference signals. The use of the MLE method for carrier tracking makes it possible to generalize the MLE equation for arbitrary codes and modulation schemes. This is ideally suited for various GNSS signals with same structure of tracking module. This paper proposes two different types of MLE based tracking method, i.e., an iterative batch processing method and a non-iterative feed-forward processing method. The first method is derived without any limitation on time consumption, while the second method is proposed for a time limited case by using a 1st derivative of cost function, which is proportional to error signal from discriminators of conventional tracking methods. The second method can be implemented by a block diagram approach for tracking carrier phase, Doppler frequency and code phase with assuming no correlation of signal parameters. Finally, a state space form of FLL/PLL/DLL is adopted to the designed MLE based tracking algorithm for reducing noise on the estimated signal parameters.

• Restorative Dentistry and Endodontics
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• v.40 no.3
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• pp.229-235
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• 2015

Objectives: To determine and compare the fracture resistance of endodontically treated maxillary central incisors restored with different posts and cores. Materials and Methods: Forty-eight upper central incisors were randomly divided into four groups: cast post and core (group 1), fiber-reinforced composite (FRC) post and composite core (group 2), composite post and core (group 3), and controls (group 4). Mesio-distal and bucco-lingual dimensions at 7 and 14 mm from the apex were compared to ensure standardization among the groups. Twelve teeth were prepared for crown restoration (group 4). Teeth in other groups were endodontically treated, decoronated at 14 mm from the apex, and prepared for posts and cores. Resin-based materials were used for cementation in groups 1 and 2. In group 3, composite was used directly to fill the post space and for core build-up. All samples were restored by standard metal crowns using glass ionomer cement, mounted at $135^{\circ}$ vertical angle, subjected to thermo-mechanical aging, and then fractured using a universal testing machine. Kruskal-Wallis and Mann-Whitney U tests were used to analyze the data. Results: Fracture resistance of the groups was as follows: Control (group 4) > cast post and core (group 1) > fiber post and composite core (group 2) > composite post and core (group 3). All samples in groups 2 and 3 fractured in restorable patterns, whereas most (58%) in group 1 were non-restorable. Conclusions: Within the limitations of this study, FRC posts showed acceptable fracture resistance with favorable fracture patterns for reconstruction of upper central incisors.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.6 no.5
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• pp.367-372
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• 2005

In this paper, we proposed a method of content-based image retrieval using variable region. Content-based image retrieval uses color histogram for the most part. But the existing color histogram methods have a disadvantage that it reduces accuracy because of quantization error and absence of spatial information. In order to overcome this, we convert color information to HSV space, quantize hue factor being pure color information, and calculate histogram of the factor. On the other hand, to solve the problem of the absence of spatial information, we select object region in consideration of color feature and region correlation. It maintains the size of region in the selected object region. But non-object region is integrated in one region. After of selection variable region, we retrieve using color feature. As the result of experimentation, the proposed method improves 10$\%$ in average of precision.

• Journal of the Korea institute for structural maintenance and inspection
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• v.17 no.5
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• pp.136-145
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• 2013

Social interest in the seismic retrofit of the structure is growing massive earthquake that occurred recently. The brittle fracture of Non-seismically designed Columns lead to full collapse of the building. In the past, cross-sectional expansion method, a steel plate reinforcing method is applied mainly in recent years, fiber-reinforced method utilizing the advantages of the composite material are preferred. However, the reinforcement methods such as this, there is a drawback to induce physical damage to structures, and time consuming work space is large. IIn this study, FRP seismic reinforcement was developed using the Aluminum connector and the composite material (Glass Fiber Reinforced Polymer). Then, the optimum quantities of FRP seismic reinforcement was determined using a nonlinear finite element analysis program. Finally, the quantity decision process through the design and analysis of FRP reinforcement was suggested.

• The Korean Journal of Pain
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• v.20 no.1
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• pp.54-59
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• 2007

Background: Selective transforaminal epidural block (STEB) has showen effectiveness as a diagnostic and therapeutic option for the management of patients with low back pain or sciatica. This study was carried out in order to determine the short-term effects and prognostic factors associated with STEB in patients with low back pain or sciatica. Methods: Ninety-seven patients were selectedfor participation in this study. Their diagnosis were based werewason the clinical symptoms and MRI findings. We performed STEB under fluoroscopic guidance and injected 3 ml of radio opaque dye in order to confirm the technical success of the procedure. We then injected 20 mg of triamcinolone mixed into 3 ml of 0.5% mepivacaine. One month later, we classified the patient outcomes as excellent, good, moderate or poor, according to the degree of reduction in VAS score from baseline. The independent variables assessed included symptom duration, block level, number of blocks, primary diagnosis, prior caudal block, anterior epidural space filling of dye, medication history, demographic data, radiating pain, back surgery and spondylolisthesis. Results: At a mean follow-up period of 1 month after STEB, excellent results were noted in the patients diagnosed with herniated lumbar disc (70%), non-specific spondylosis (54%), spinal stenosis (44%), and failed back syndrome (28%). The patients with epidural adhesion and combined spondylolisthesis were associated with poorer outcomes. Combined caudal block, symptom duration and the extent of epidural spread of the drug were not related to the effectiveness of the treatment. Conclusions: Selective transforaminal epidural block is effective in treating patients with radiculopathy, such as herniated lumbar disc, but it isrelatively ineffective in treating patients with structural deformities, such as failed back syndrome and spondylolisthesis.

• The Journal of the Korea Contents Association
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• v.17 no.9
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• pp.60-68
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• 2017

Through this thesis, I wanted to understand the form of free indirect discourse of modern films. To this end, I first explored the notion of the polyphonie as a mixture of the speaker and the character' voice in order to establish a concept related to free indirect discourse. However, I could not overlook the differences in the form of novels and movies to apply the following theory to films. Based on the concept of narrative distance, I sought to explore the possibility of free indirect discourse from the dual position of the camera. Next, I introduced the concept of free indirect discourse in the film by introducing the concept of Time in G. Deleuze' CinemaII. In other words, the time from Deleuze is the past and the present cycle, and he sees the Time circulating like the Non-Euclidean space. I wanted to understand the form of free indirect discourse in films by analyzing the concept of Time as an analysis of the movie .

• Archives of design research
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• v.12 no.2
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• pp.19-28
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• 1999

Current technology does not emphasize closer connection through group collaboration, but rather underlines the distances and separations that are visible in today's society. As the interpretation of our territory of life which is still based on the model of the 'physical' of industrial era is no more valid, a different 'sense of belonging' corresponds to this new notion of territory. The main idea is how to make the sense of community to connect actual space with one child from each place. Therefore, the subject of this thesis is to design the system making children from distance to be closer, developing 'learning community' connecting with two classes across the globe. The contents include its studying in respect to the development of a non-geographical 'learning community' based on co-evolution, and to the system design of conceptual models for the community. In conclusion, the physical interface design is suggested to let user develop accurate mental models of the system.

• Archives of design research
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• no.16
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• pp.237-252
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• 1996

Study of new materials, which has been going on in many fields of modem art since the beginning of this century, has cintributed much to the development of modem art. In this regard, it is noteworthy that many in the field of fiber art have experimented with non-traditional, indusrial materials with some notable success. Industrial materials represent the world of thechnology we live in and help us form the kind of view on art that is reflective of the present age and its social milieu. Industrial materials, when used as media for art, also present us with new concepts and possibilities for artistic expression. In fiber art, the use of industrial materials has greatly expanded the very idea of 'fiber', effectively ferring the imagination of fiber aetists to experiment with diverse materials and new mathodology. Overcoming the traditional constraints of technique-orienthd their discipline, fiber artists began to pay more attention to matiere or the material jtself and the infinite variety of surface, color and texture that it promises. And informed by this newly discovered aesthetice of the material. fiber artists began in eamest to expand the area of their artistic expression, producing multi-dimensional works, conquering space and experimentiong with hugc environmantal works.

• Korean Institute of Interior Design Journal
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• v.19 no.1
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• pp.37-45
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• 2010

Children likes to play and learn by playing at anywhere as a psychological trait. Children's museum is designed for limited age of 'children,' they learn more actively by playing at the museum with interactive display. In this paper, we analyze Movement of Based on the Psychological Characteristics of Children and Analysis of Preferred Experience of Children's Museum according to Piaget's cognitive development process. It is significant study to investigate user's needs space proposal by grasping user's mentality. After itinerary tracking, we found children's preferred and non-preferred experience displays and as a result, we divided children's Museums into three types, M museum is represented by preoperational period, called 'Go around play' type ; Y museum is represented by 'concrete operational period', called 'Smart road play' type ; and H museum is represented by 'formal operational period' called 'Open search play' type. The conclusions are children's cognitive development stages depending on the age discrimination that the development of play, and preferred plays are different by children cognitive development process. In order to take advantage of children playing in the children's museum by taking into account the developmental aspects will have to be designed. Efficient for viewing by age should be different on the basis. This study has shown that, when planning a children's museum, Planners should discriminate the movements of children and analysis of preferred experience of children's museum according to three museum types friendly to children's cognitive development process.