• The korean journal of orthodontics
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• v.32 no.2 s.91
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• pp.107-115
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• 2002

The aim of this study was to investigate experimentally the mechanical and histological effect of drilling process on the stability of micro-implant used for the orthodontic anchorage. For this purpose, 32 micro-implants(Osas$^{(R)}$, Epoch medical, ${\phi}$1.6 mm) were inserted into maxilla, mandible and palate in two beagle dogs. 16 micro-implants(8 per dog) were inserted after drilling with pilot drilling bur (drill method group). 16 micro-implants(8 per dog) were inserted without drilling (drill-free method group). After 1 week, micro-implants were loaded by means of Ni-Ti coil spring (Ni-Ti springs-extension$^{(R)}$, Ormco) with 200-300 gm force. Following 12 weeks, the micro-implants and the surrounding bone were removed. Before sacrifice, the mobilities were tested with Periotest$^{(R)}$(Siemens). Undecalcified serial sections with the long axis were made and the histologic evaluations were done. The results of this study were as follow ; 1. The osseointegration was found in both of drill-free method group and drill method group 2. Two of drill method group and one of drill-free method group in 32 micro-implants were lost after loading. 3. The mobilities of drill-free method group were less than drill method group 4. The bone contact on surface of micro-implants in drill-free method group was more than drill method group but there was no significant difference between groups. 5. The bone density in threads of micro-implants in drill-free method group was more than drill method group and there was significant difference between groups. These results suggest that drill-free method in insertion of micro-implants is superior to drill method on the stabilities, bone remodeling and osseointegrations under early loading.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.40 no.5
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• pp.312-321
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• 2003

In this paper, we implement robot which are ability to recognize obstacles and moving automatically to destination. we present two results in this paper; hardware implementation of image processing board and software implementation of visual feedback algorithm for a self-controlled robot. In the first part, the mobile robot depends on commands from a control board which is doing image processing part. We have studied the self controlled mobile robot system equipped with a CCD camera for a long time. This robot system consists of a image processing board implemented with DSPs, a stepping motor, a CCD camera. We will propose an algorithm in which commands are delivered for the robot to move in the planned path. The distance that the robot is supposed to move is calculated on the basis of the absolute coordinate and the coordinate of the target spot. And the image signal acquired by the CCD camera mounted on the robot is captured at every sampling time in order for the robot to automatically avoid the obstacle and finally to reach the destination. The image processing board consists of DSP (TMS320VC33), ADV611, SAA7111, ADV7l76A, CPLD(EPM7256ATC144), and SRAM memories. In the second part, the visual feedback control has two types of vision algorithms: obstacle avoidance and path planning. The first algorithm is cell, part of the image divided by blob analysis. We will do image preprocessing to improve the input image. This image preprocessing consists of filtering, edge detection, NOR converting, and threshold-ing. This major image processing includes labeling, segmentation, and pixel density calculation. In the second algorithm, after an image frame went through preprocessing (edge detection, converting, thresholding), the histogram is measured vertically (the y-axis direction). Then, the binary histogram of the image shows waveforms with only black and white variations. Here we use the fact that since obstacles appear as sectional diagrams as if they were walls, there is no variation in the histogram. The intensities of the line histogram are measured as vertically at intervals of 20 pixels. So, we can find uniform and nonuniform regions of the waveforms and define the period of uniform waveforms as an obstacle region. We can see that the algorithm is very useful for the robot to move avoiding obstacles.

• Journal of the korean academy of Pediatric Dentistry
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• v.28 no.3
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• pp.504-511
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• 2001

Preventive resin restoration, extended concept of occlusal pit and fissure sealing, is procedure composed of as follows. Cavity preparation is limited to areas of initial caries The cavity is then restored with composite resin, while other sound pits and fissures are sealed with pit and fissure sealant. If pit and assure sealant with which microrestoration is possible is used, it may be of great benefit to both patient and operator in case of difficult-to-control children s treatment. However study on preventive resin restoration using this kind of materials have been scarce. The purpose of this study was to compare the microleakage of four different modes of preventive resin restoration. Restoration using only composite resin was compared together Fifty-five bicuspids were prepared with small class I cavity preparation on the occlusal surface, divided into the following groups and restored accordingly. Group 1 : Cavity was restored with Z-100 composite resin Group 2 : Cavity was restored with Z-100 composite resin. Pits and fissures were then sealed with Teethmate F-1 Group 3 : Cavity was restored with Z-100 composite resin Pits and fissures were then sealed with Ultraseal XT-plus Group 4 : Cavity and pits and fissures were restored with Ultraseal XT-plus altogrether Group 5 : Cavity was restored with Ultraseal XT-plus. Pits and fissures were then sealed with the same material. After restoration, the samples were thermocycled 500 times between $5^{\circ}C$ and $55^{\circ}C$ with a dwell time of 30 seconds. After thermocycling, the samples were dipped into 1% methylene blue solution for 24 hours, then rinsed with tap water. The teeth were then embedded in resin and cut buccolingually along the tooth axis and observed with a stereomicroscope to determine the degree of microleakage. The results were as follows : 1. Group 4 showed the greatest microleakage, while group 3, showed the least. The mean microleakage decreased in the following order:4>1>5>2>3. 2. There was no stastically significant difference between group 1 and group 5(p>0.05). However, group 1 showed significantly greater microleakage compared to group 2 and 3(p<0.05) Group 1 showed significantly less microleakage compared to group 4(p<0.05). 3. Group 2 showed no statistically significant difference compared to group 3(p>0.05). However group 2 showed significantly less microleakage compared to group 4 and 5(p<0.05) 4. Group 3 showed significantly less microleakage compared to group 4 and 5(p<0.05). 5. Group 5 showed significantly less microleakage than group 4(p<0.05).

• Journal of the korean academy of Pediatric Dentistry
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• v.35 no.2
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• pp.278-286
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• 2008

Many studies regarding Casein phosphopeptides-amorphous calcium phosphate(CPP-ACP) have demonstrated the remineralization ability on the demineralized enamel surface. A question is still remained that how deep can the calcium (Ca) and phosphorus (P) ions supplied by the CPP-ACP paste penetrate into the enamel subsurface. The aims of this study were to measure the penetrating depth of Ca and P ions in the demineralized human enamel in vitro, and were to determine the amount and depth of Ca and P ions according to the duration. The amount and depth of Ca and P ions were measured by microscopic observation with Field Emission Scanning Electron Microscopy (FE-SEM; LEO SUPRA 55, Carl Zeiss, Germany) and Energy Dispersive X-ray Spectrometer (EDS; GENESIS 2000, EDAX, USA: Linescan of Calcium and Phosphorus). Freshly extracted four human 1st premolars were obtained from the Dept. of Pediatric Dent., Kyung Hee Univ. Buccal surfaces of the 1st premolars were covered with nail varnish to form a window on the middle third of buccal surface. All of the teeth with enamel windows were immersed in a solution of 0.1 M lactic acid, Carbopol C907 (carboxypolymethylene BF Goodrich, Cleveland, OH, USA) at pH 4.8, and then incubated for 7 days. Each tooth crown was sawn in half through the midline of buccal window along the long axis of premolar. The four blocks of premolars were immersed in a 10-times diluted solution of CPP-ACP paste (Tooth Mousse, GC Corp., Tokyo, Japan) for 1, 2, 3 and 5 weeks while the rests were immersed in a placebo solution (distilled water) for the same duration. Each specimen was embedded in epoxy resin, and was sectioned perpendicular to the window, using a water-cooled diamond blade saw. The spectrum density indices of Ca and P were measured in the sound, de- and remineralized enamels by FE-SEM and EDS. The Student's t test was performed to compare the Spectrum Density Indices (SDI) of sound, re-and demineralized enamels, and to compare the differences among the durations. Followings are the conclusion : 1. The penetration depth of the remineralizing ions (Ca & P) of CPP-ACP paste is related to the depth of demineralized enamel (approximately $1050{\sim}1350{\mu}m$). It is revealed that the penetration depth of both ions reaches full thickness of decalcification and even slightly into the sound enamel. 2. The Ca & P levels of remineralized enamels in 1, 2 weeks were significantly higher than those of the sound enamels (p<0.05). 3. No statistically significant difference of Ca & P levels was found in relation with the increasing duration of remineralization (p>0.05).

• Progress in Medical Physics
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• v.10 no.3
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• pp.133-140
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• 1999

In this paper, as a preliminary study for developing a full 3D electron dose calculation algorithm, We developed 2.5D electron dose calculation algorithm by extending 2D pencil-beam model to consider three dimensional geometry such as air-gap and obliquity appropriately. The dose calculation algorithm was implemented using the IDL5.2(Research Systems Inc., USA), For calculation of the Hogstrom's pencil-beam algorithm, the measured data of the central-axis depth-dose for 12 MeV(Siemens M6740) and the linear stopping power and the linear scattering power of water and air from ICRU report 35 was used. To evaluate the accuracy of the implemented program, we compared the calculated dose distribution with the film measurements in the three situations; the normal incident beam, the 45$^{\circ}$ oblique incident beam, and the beam incident on the pit-shaped phantom. As results, about 120 seconds had been required on the PC (Pentium III 450MHz) to calculate dose distribution of a single beam. It needs some optimizing methods to speed up the dose calculation. For the accuracy of dose calculation, in the case of the normal incident beam of the regular and irregular shaped field, at the rapid dose gradient region of penumbra, the errors were within $\pm$3 mm and the dose profiles were agreed within 5%. However, the discrepancy between the calculation and the measurement were about 10% for the oblique incident beam and the beam incident on the pit-shaped phantom. In conclusions, we expended 2D pencil-beam algorithm to take into account the three dimensional geometry of the patient. And also, as well as the dose calculation of irregular field, the irregular shaped body contour and the air-gap could be considered appropriately in the implemented program. In the near future, the more accurate algorithm will be implemented considering inhomogeneity correction using CT, and at that time, the program can be used as a tool for educational and research purpose. This study was supported by a grant (＃HMP-98-G-1-016) of the HAN(Highly Advanced National) Project, Ministry of Health & Welfare, R.O.K.

• Korean Journal of Heritage: History & Science
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• v.53 no.1
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• pp.64-87
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• 2020

The cultural property management system of Korea was established based on the modern cultural assets acts and the old imperial estate management system enacted during the Japanese occupation. Academics have researched the cultural property management system oriented on the modern cultural assets acts, but few studies have been conducted into the old imperial estate management system, which is another axis of the cultural property management system. The old imperial estate was separated from the feudal capital by the Kabo Reform, but was dismantled during the colonial invasion of Japan and managed as a hereditary property of the colonial royal family during the Japanese colonial period. After establishment of the government, the Imperial Estate Act was enacted in 1954 and defined the estate as a historical cultural property managed by the Imperial Estate Administration Office. At this time, imperial estate property that was designated as permanent preservation property was officially recognized as constituting state-owned cultural assets and public goods in accordance with Article 2 of the Act's supplementary provisions during 1963, when the first amendment to the Cultural Property Protection act was implemented. In conclusion, Korea's cultural property formation and cultural property management system were integrated into one unit from two different sources: modern cultural assets acts and the old imperial estate property management system. If the change of modern cultural assets acts was the process of regulating and managing cultural property by transplanting and applying regulations from Japan to colonial Joseon, the management of the imperial estate was a process by which the Japanese colonized the Korean Empire and disposed of the imperial estate. Independence and the establishment of the government of the Republic of Korea provided the opportunity to combine these two different streams into one. Finally, this integration was completed with the establishment of the Protection of Cultural Properties Act in 1962.

• Cartoon and Animation Studies
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• s.49
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• pp.633-649
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• 2017

The purpose of this study is to conceptualize the changing aspects of human freedom of observation and viewing as the visual media evolves from film to 3D stereoscopic film and VR. The purpose of this study is to conceptualize the aspect of freedom and viewing aspect from the viewpoint of genealogy. In addition, I will identify the media aesthetic characteristics of VR and identify the identity and ontology of VR. Media has evolved around the most artificial sense of human being. There is a third visual space called screen at the center of all the reproduction devices centering on visual media such as painting, film, television, and computer. In particular, movies, television, and video screens, which are media that reproduce moving images, pursue perfect fantasy and visual satisfaction while controlling the movement of the audience. A mobilized virtual gaze was secured on the assumption of the floating nature of the so-called viewers. The audience sees a cinematic illusion with a view while seated in a fixed seat in a floating posture. They accept passive, passive, and passively without a doubt the fantasy world beyond the screen. But with the advent of digital paradigm, the evolution of visual media creates a big change in the tradition of reproduction media. 3D stereoscopic film predicted the extinction of the fourth wall, the fourth wall. The audience is no longer sitting in a fixed seat and only staring at the front. The Z-axis appearance of the 3D stereoscopic image reorganizes the space of the story. The viewer's gaze also extends from 'front' to 'top, bottom, left, right' and even 'front and back'. It also transforms the passive audience into an active, interactive, and experiential subject by placing viewers between images. Going one step further, the visual media, which entered the VR era, give freedom to the body of the captive audience. VR secures the possibility of movement of visitors and simultaneously coexists with virtual space and physical space. Therefore, the audience of the VR contents acquires an integrated identity on the premise of participation and movement. It is not a so-called representation but a perfection of the aesthetic system by reconstructing the space of fantasy while inheriting the simulation tradition of the screen.

• International Journal of Highway Engineering
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• v.14 no.3
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• pp.97-110
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• 2012

In case of the axial line bikeway, the residents in the riverside use it frequently but those in the city center hardly do as the axis is formed along the riverside of the Han river. This situation happens due to the inefficient connectivity between the bikeway that leads to the riverside and that in the city center, which means the administrative policies have been focused on the facilities rather than on raising connectivity of the bikeway networks in the south of the Han River. Also, this is the point of time when a reasonable improvement plan is needed to raise the accessibilities of the bikeways in Seoul, not just a utilization of those in the south of the Han River. This study intends to analyse the connectivity between Gangseo (west of the Han River) and Gangdong (East of the Han River) districts by comparing the current spatial structure in the southern areas of the Han River and that after the installation of the axial line, and that after installation of the ordinary bikeway respectively with use of the Space Syntax Model, and to predict resultant changes there of. The Space Syntax Model was used as the major method of analysis in this study to find out characteristics of the bikeways in the south of the Han River. Consequently, as the analysis shows that when the bikeways in the Gangseo and Gangdong-gu districts are connected, the accessibility of the bikeways in the south of the Han River will improve while the spatial structure intelligibility will be lowered, it can be said the prediction rate in the all areas is low compared with the current status. It is analyzed that the intelligibility of the current bikeways in the south of the Han River appeared highest when compared with those of plans for installation of the axial line and ordinary bikeway because they don't interconnect with other areas.

• Radiation Oncology Journal
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• v.18 no.2
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• pp.107-113
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• 2000

Purpose : The goal of this study 닌as to improve the accuracy of three-dimensional conformal radiotherapy (3-D CRT) by measuring the treatment setup error and physiological movement of liver based on the analysis of images which were obtained by electronic portal imaging device (EPID). Materials and Methods : For 10 patients with hepatocellular carcinoma, 4-7 portal images were obtained by using EPID during the radiotherapy from each patient daiiy. We analyzed the setup error and physiological movement of liver based on the verification data. We also determined the safety margin of the tumor in 3-D CRT through the analysis of physiological movement. Results : The setup errors were measured as 3mm with standard deviation 1.70 mm in x direction and 3.7 mm with standard deviation 1.88 mm in y direction respectively. Hence, deviation were smaller than 5mm from the center of each axis. The measured range of liver movement due to the physiological motion was 8.63 mm on the average. Considering the motion of liver and setup error, the safety margin of tumor was at least 15 mm. Conclusion : EPID is a very useful device for the determination of the optimal margin of the tumor, and thus enhance the accuracy and stability of the 3-D CRT in patients with hepatocellular carcinoma.

• Journal of the Korean Society of Radiology
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• v.10 no.8
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• pp.603-610
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• 2016

This study was performed to analyze the results of radiologic parameters compared both leg weight bearing position to single leg weight bearing position in ankle osteoarthritis. Between January 2016 and June 2016, 25 patients (50 ankles) who visited our Hospital to treat ankle pain. In radiographic assessment, We masured tibial anterior surface angle(TAS), tibial medial malleolar angle(TMM), talar tilting angle(TT), joint space width(JSW), tibiotalar joint space, fibulotalar joint space of ankle as radiologic parameters. On the right leg of the both leg weight bearing position, TAS was $87.24^{\circ}$, TT was $6.44^{\circ}$, TMM was $26.76^{\circ}$, fibulotalar joint space was 0.98mm. Right leg of the single leg weight bearing position, TAS was $88.93^{\circ}$, TT was $2.41^{\circ}$, TMM was $19.77^{\circ}$, fibulotalar joint space was 1.6mm. And then, on the left leg of the both leg weight bearing position, TAS was $87.25^{\circ}$, TT was $5.71^{\circ}$, TMM was $23.92^{\circ}$, fibulotalar joint space was 1.22 mm and left leg of the single weight bearing position, TAS was 88.75, TT was $3.19^{\circ}$, TMM $21.45^{\circ}$, fibulotalar joint space was 1.22 mm. There are unsimilarity between measure values of TAS and tibiotalar joint space. As the result of test of weight bearing ankle study, it would be more exact to examine to measure one side in the first time rather than both to conclude on accurate measurement.