• Journal of Sensor Science and Technology
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• v.5 no.4
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• pp.1-7
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• 1996

Optical intensity-type pressure sensor was fabricated by coupling optical fiber with a micromachined thin dielectric diaphragm, which consists of a 300 nm thick $SiO_{2}$ layer sandwiched between 150 nm thick top and bottom $Si_{3}N_{4}$ layers. At the wavelength of the sensor light source near $1.3\;{\mu}m$, the optical transmittance of the diaphragm was about 50 %, but it was decreased to a few percents by depositing $1,000\;{\AA}$ thick gold(Au) layer on the diaphragm, which is sufficient enough to be used as a light reflection layer of the sensor. From the optical output power-pressure characteristics of the sensors, it was found that the output power linearly decreased with increasing applied pressure from 0 to 77 torr regardless of the diaphragm size. The respective sensitivities were 0.52, 0.65, and 0.77 nW/torr for the diaphragm sizes of $3{\times}3$, $4{\times}4$, and $5{\times}5\;mm^{2}$, indicating that the sensitivity increases as diaphragm size decreases.

• The Journal of the Korean dental association
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• v.58 no.7
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• pp.435-442
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• 2020

Porcelain is the first ceramic material to be introduced into dentistry. Porcelain jacket crown was introduced by Dr. Charles H Land in 1886, which was an excellent aesthetic dental restoration but has not been widely used due to high firing shrinkage and low tensile strength. Then metal-ceramic system, which combines the esthetic properties of ceramics and the mechanical properties of metals, was introduced and nowadays it is still used in dental clinical field. However, the metal-ceramic system has shown some problems, such as increased lightness by reflection of light at opaque layer, shadow beneath the gingival line due to the block-out of light by metal coping, exposure of metal in margin part, bond failure between metal and porcelain, oxidation of metal coping during firing the porcelain, etc. Recently, along with the advance of fabrication methods of dental ceramics, the all-ceramic restorations with high esthetic and mechanical properties has increased and gradually replaced metal-ceramic restorations. Especially, CAD/CAM technology has opened a new era in fabricating the dental ceramic restorations. This overview will take a look at the past, present and future possibility of the dental ceramic materials.

• Journal of The Korean Association For Science Education
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• v.24 no.6
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• pp.1189-1205
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• 2004

The purpose of this study is to understand the types of teacher and student's concept on ray-tracing and spectrum in middle school. This study suggest key-concepts that is most important to "Light" unit in the seven grades: the ray-tracing and the spectrum. We examined the types of teacher and student's concept. We selected 10 teacher and 328 students who had learned by 10 teachers in Seoul and Gyeonggi. The problems were composed with the question item regarding all ray-tracing or the spectrum. From the analysis, it was found that the types of teacher and student's concept on ray-tracing and spectrum is different. The most of teacher and student didn't understand the basic principle of image formation. In case of context about formation of image by reflection and refraction, because they don't know ray-tracing, they do not try to find the position of the image by drawing two rays. Most of them used one ray comes from the one position of the object and indicated the position of image by memorized position. Also almost there was not a case which uses a ray tracing accurately. In the case of understanding color, they didn't understand the concept of color(or spectrum) and teachers represented to students the color phenomena without explanation of principles. In the result teachers and students would learn color science by rote.

• Journal of the Korean Society of Costume
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• v.20
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• pp.125-135
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• 1993

The purposes of this research are firstly to define the characteristics of movement on the costume, secondly to demonstrate that fine art, expecially in relation to kinetic art, has become a good motif in modern costume de-sign, and thirdly to examin the characteristics of movement as shown in modern costume de-sign. For this study, we selected and analyzed some costume designs among those introduced in fashion magazines, which are Collections, Fashion-Preview, Fashion Show, Collezioni, and L'Officiel that have been issued since 1988. As this research is carried out only through the analysis of pictures, it is not ac-companied by a study on material itself. The result of this study is that the ex-pression of movement on modern fashion can be shown in two ways, one is the inclusive and subordinate movement expressed on the cloth-ing according to the motion of body when they are worn, and the other is the movement caused by the very designs of clothing. And the latter can be also divided in two ways, the illusionistic movement and the actual move-ment. The expression of actual movement is made through the emphasis of direction, rhythm, and dimension of the costume. And the illusionistic movement is expressed by the de-sign to which the textile pattern or reflection of light is applied so that the movement is larger than the actual movement. A sense of direction expressed on the cos-tume by the actual movement creates a light rhythm and adds interest to the costume. This reflects a part of psychology of modern men who are not accustomed to the statics. In the rapidly changing society of information our modern men seek after movement even in the statics. It is also true in the clothing and they seem to get a psychological rest through the immediated visual change as shown in fashion design. The simple and cheerful rhythm expressed by the illusionistic movement on the costume is attempted in order to overcome the static tediousness caused by simple design. These elements of movement cause the en-largement of visible range and create another enlarged shape other than the real one, so that they come to remove the dullness and monot-ony in costume design and provoke interest in costume, as if kinetic art reveals the various aspects that transcend the closed area of fine art upon the motif of 'movement'. finally, as this paper deals with the ex-pression of movement as shown in the costume design which prevailed after 1988, it is desir-able hereafter to study more about the fashion since 1950 when kinetic art began in earnest, along with the comparative study on the ex-pression of movement in our Korean designer's and foreign designer's works.

• Journal of the Korean Vacuum Society
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• v.22 no.1
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• pp.13-19
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• 2013

It is expected that progress in building-integrated photovoltaic (BIPV) systems, improving the functionality and design of buildings, will be accelerated in the coming years. While the dye sensitized solar cell is considered one of the most important technologies in the BIPV field, the transparent silicon based thin film solar cell fabricated by thin film processes has drawn attention as a novel alternative. When the selective transmitting layer is applied to the solar cell, the conversion efficiency is improved due to the re-reflection of infrared light into an absorber layer with the transmission of visible light through the solar cell. In this work, we prepared Al-Ti based oxide thin films using cost-effective sputter deposition and examined their selective transmitting characteristics with various compositions. The transmittance and reflectance of the Al-Ti based oxide thin film changed with the variation of its composition, and the selective transmitting property was observed in the sample with the 25 nm-thick AlTiO layer. It is considered that the realization of transparent solar cells and the improvement of their conversion efficiency can be achieved by introducing the Al-Ti based selective transmitting layer.

• Restorative Dentistry and Endodontics
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• v.22 no.1
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• pp.358-373
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• 1997

Resin modified glass ionomers were introduced in 1988 to overcome the problems of moisture sensitivity and low early mechanical strength of conventional glass ionomers and to maintain their clinical advantages. The purpose of this study was to evaluate the color stability of four resin modified glass ionomers(Fuji II LC, Vitremer, Dyract and VariGlass), one resin composite material(Z-100), and one conventional glass ionomer(GC Fuji II) under several conditions. These conditions were as follows: 1) before curing, 2) after curing, 3) after polishing, 4) after 500 thermocycling, 5) after 1,000 thermocycling, 6) after 1,500 thermocycling and 7) after 2,000 thermocycling. Three specimens of each material/shade combination were made. Materials were condensed into metal mold with a diameter of 10 mm and a thickness of 2.0 mm, and were pressed between glass plates. The material was polymerized using a light polymerizing unit(Visilux II, 3M, USA). After removal of excess, the surface was polished sequentially on wet sandpapers. A reflection spectrophotometer(Model TC-6FX, Tokyo Denshoku Co., Japan) was used to determine CIELAB coordinates($L^*,a^*$ and $b^*$) of each specimen. CIE standard illumination C was used as the light source. The results were as follows : 1. In comparing different shades of same material, CIELAB color difference(${\Delta}E^*$) value was not significantly different from each other(p>0.05). 2. CIELAB color difference(${\Delta}E^*$) values between after-curing and after-polishing were ranged from 5.53 to 27.08. These values were higher than those of other condition combinations. 3. CIELAB color difference(${\Delta}E^*$) values between before-thermocycling and after-thermocycling were ranged from 1.40 to 7.81. Despite the number of thermocycling increased, CIELAB color difference(${\Delta}E^*$) value was low. 4. The color stability of resin modified glass ionomers was more stable than that of conventional glass ionomers but less stable than that of Z100.

• Journal of The Korean Association For Science Education
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• v.24 no.5
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• pp.1008-1017
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• 2004

In physics education, language is an fundamental learning tool as in other subjects. In writing activity, students can get fair opportunities to express their own ideas during the class. Even though there are various styles of writing, students are usually supposed to make a report in their science classes. But there have been few studies in science education on the tasks and features of student's science writing. In this research, different styles of writing tasks were designed for science classes, and students' writing was analysed in terms of conceptual and emotional aspects. Also the usefulness of each task type was discussed relating to school physics education. Four types of writing, i.e. , , , and writing were developed, and 'The reflection of light' was selected as the theme and given to students. Four types of writing were analysed in this paper. In each type of writing, students showed different features in their conception. They also showed emotional expressions in imaginative writing types, that is, and types. Based on these results, it is recommended that in physics teaching various types of writing need to be designed, developed and applied according to the aim of a particular lesson.

• The Journal of Engineering Geology
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• v.12 no.4
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• pp.405-419
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• 2002

Fracture roughness of rock specimens is observed by a new confocal laser scanning microscope (CLSM; Olympus OLS1100). The wave length of laser is 488 nm, and the laser scanning is managed by a light polarization method using two galvano-meter scanner mirrors. The function of laser reflection auto-focusing enables us to measure line data fast and precisely. The system improves resolution in the light axis (namely z) direction because of the confocal optics. Using the CLSM, it is Possible to measure a specimen of the size up to $10{\;}{\times}{\;}10{\;}cm$ which is fixed on a specially designed stage. A sampling is managed in a spacing $2.5{\;}\mu\textrm{m}$ along x and y directions. The highest measurement resolution of z direction is $10{\;}\mu\textrm{m}$, which is more accurate than other methods. Core specimens of coarse and fine grained granite are provided. Fractures are artificially maneuvered by a Brazilian test method. Measurements are performed along three scan lines on each fracture surface. The measured data are represented as 2-D and 3-D digital images showing detailed features of roughness. Line profiles of the coarse granites represent more frequent change of undulation than those of the fine granite. Spectral analyses by the fast Fourier transform (FFT) are performed to characterize the roughness data quantitatively and to identify influential frequency of roughness. The FFT results suggest that a specimen loaded by large and low frequency energy tends to have high values of undulation change and large wave length of fracture roughness.

• Korean Journal of Remote Sensing
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• v.20 no.5
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• pp.289-305
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• 2004

Atmospheric correction of Landsat Visible and Near Infrared imagery (VIS/NIR) over aquatic environment is more demanding than over land because the signal from the water column is small and it carries immense information about biogeochemical variables in the ocean. This paper introduces two methods, a modified dark-pixel substraction technique (path--extraction) and our spectral shape matching method (SSMM), for the correction of the atmospheric effects in the Landsat VIS/NIR imagery in relation to the retrieval of meaningful information about the ocean color, especially from Case-2 waters (Morel and Prieur, 1977) around Korean peninsula. The results of these methods are compared with the classical atmospheric correction approaches based on the 6S radiative transfer model and standard SeaWiFS atmospheric algorithm. The atmospheric correction scheme using 6S radiative transfer code assumes a standard atmosphere with constant aerosol loading and a uniform, Lambertian surface, while the path-extraction assumes that the total radiance (L/sub TOA/) of a pixel of the black ocean (referred by Antoine and Morel, 1999) in a given image is considered as the path signal, which remains constant over, at least, the sub scene of Landsat VIS/NIR imagery. The assumption of SSMM is nearly similar, but it extracts the path signal from the L/sub TOA/ by matching-up the in-situ data of water-leaving radiance, for typical clear and turbid waters, and extrapolate it to be the spatially homogeneous contribution of the scattered signal after complex interaction of light with atmospheric aerosols and Raleigh particles, and direct reflection of light on the sea surface. The overall shape and magnitude of radiance or reflectance spectra of the atmospherically corrected Landsat VIS/NIR imagery by SSMM appears to have good agreement with the in-situ spectra collected for clear and turbid waters, while path-extraction over turbid waters though often reproduces in-situ spectra, but yields significant errors for clear waters due to the invalid assumption of zero water-leaving radiance for the black ocean pixels. Because of the standard atmosphere with constant aerosols and models adopted in 6S radiative transfer code, a large error is possible between the retrieved and in-situ spectra. The efficiency of spectral shape matching has also been explored, using SeaWiFS imagery for turbid waters and compared with that of the standard SeaWiFS atmospheric correction algorithm, which falls in highly turbid waters, due to the assumption that values of water-leaving radiance in the two NIR bands are negligible to enable retrieval of aerosol reflectance in the correction of ocean color imagery. Validation suggests that accurate the retrieval of water-leaving radiance is not feasible with the invalid assumption of the classical algorithms, but is feasible with SSMM.

• KIPS Transactions on Computer and Communication Systems
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• v.11 no.10
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• pp.345-352
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• 2022

Recent LiDAR(Light Detection And Ranging) sensor is used for scanning object around in real-time. This sensor can detect movement of the object and how it has changed. As the production cost of the sensors has been decreased, LiDAR begins to be used for various industries such as facility guard, smart city and self-driving car. However, LiDAR has a large input data size due to its real-time scanning process. So another way for processing a large amount of data are needed in LiDAR system because it can cause a bottleneck. This paper proposes edge computing to compress massive point cloud for processing quickly. Since laser's reflection range of LiDAR sensor is limited, multiple LiDAR should be used to scan a large area. In this reason multiple LiDAR sensor's data should be processed at once to detect or recognize object in real-time. Edge computer compress point cloud efficiently to accelerate data processing and decompress every data in the main cloud in real-time. In this way user can control LiDAR sensor in the main system without any bottleneck. The system we suggest solves the bottleneck which was problem on the cloud based method by applying edge computing service.