• Imaging Science in Dentistry
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• v.32 no.1
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• pp.11-18
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• 2002

Purpose: To evaluate cultured human artificial skin as an experimental model for studying radiation effects in vitro. Materials and Methods: The skin was constructed by culturing keratinocytes over collagen lattice which made by culturing fibroblasts. Two groups were irradiated to gamma rays at single dose of 25 Gy with or without 3.5% of DMSO. Ultrastructures were investigated by electron microscopy after irradiation. The number of epidermal layers and expression of cytokeratin (CK) 14 & 10 were also seem by light microscopy. Results: At 2 days after irradiation in experimental group without DMSO, necrotic cells were rarely found in the spinosal layer and undercornified cells were visible in the homey layer. Similar findings were also found in experimental group with DMSO but in mild form. The number of epidermal layers in experimental group without DMSO were significantly fewer than other group. CK 14 expressed in all the layer excluding homey layer but CK 10 expressed over 3∼4 basal layers. Such patterns of CK expression were similar to all groups. It is suggested that structures of the keratinocytes and epidermal formation could be disturbed by irradiation in artificial skin and that DMSO can protect these damages. Conclusion : Therefore this work could be used as an organotypic experimental model in vitro using human cells for studying radiation effect in skin. Furthermore structural findings provided in this study could be used as useful basic data in further study using this model.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.42 no.1
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• pp.7-12
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• 2010

Morphological characteristics of hemp fiber were investigated using a light microscope in order to provide fundamental data for the use of hemp as a papermaking law material. Phloem of hemp is composed of cortical parenchyma cells and bast fiber with thick walls while xylem is composed of vessel, wood fiber and ray parenchyma cells. Also there are solitary pore and radial pore multiple which exist in diffuse porous pattern. Ray cells consist of uniseriate rays and thin walled ray parenchyma cells. Wood fibers are composed of three types: a large diameter fiber with longer length; a large diameter fiber with shorter length; a small diameter fiber with medium length. Vessel elements are composed of: a medium length one; a longer length one; the one whose both end walls have ligules or tails. Parenchyma cells in xylem and pit parenchyma cells have completely different size and shape. For bast fiber, the average length is about 4.4 mm and the width is about $30.5\;{\mu}m$; for vessel element, $600.0\;{\mu}m$ in length and $493.6\;{\mu}m$ in width; for wood fiber, $1000\;{\mu}m$ and $38.9\;{\mu}m$; for parenchyma cell, $50\;{\mu}m$ and $26.4\;{\mu}m$.

• Analytical Science and Technology
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• v.6 no.5
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• pp.501-508
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• 1993

In n/${\gamma}$ mixed field of $^{241}Am-Be$(${\alpha}$, n) neutron source, we seperated the neutron component from gamma ray component. At the center of the detector, $^6Li$ was doped on the cerium activated glass plate for $^6Li$(${\alpha}$, n)T nuclear reaction. The time differences of the light following excitations by different scintillators, BC501($C_8H_{10}$) and cerium, and by the same scintillator for different radiations as neutrons and gamma-rays are used to apply the methods of PSD(Pulse Shape Discriminator) and CFD(Constant Fraction Discriminator). The figure of merit of $^6Li$ fast neutron spectrometer is estimated as 1.36.

• The Journal of Korean Academy of Prosthodontics
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• v.30 no.2
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• pp.167-189
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• 1992

Frictional heat produced by cutting tools during dental implantation procedure may destroy the surrounding bone tissue and regenerative capacity and interfere ossointegration by formation of undifferentiated connective tissue. To study the effect of frictional heat according to various rotational speeds on the regenerative capacity of surrounding bone tissue, 13 ITI HS implants (8 mm) were inserted at 4 mongrel dogs. Temperatures were measured using thermocouple located 6 mm below from the marginal crest and 0.5 mm from the periphery of trephine mill during implant bed preparation. After 4 and 9 months, animals were sacrificed and specimens were examined using x-rays and light microscope. Results were as follows: 1. With drill speeds of 300, 800, 2,000, 3,500 rpm and saline irrigation, temperatures of surrounding bone were decreased from $-2.9^{\circ}\;to\;-1.7^{\circ}C$. Temperature rises of $2.0^{\circ}\;and\;2.1^{\circ}C$ were recorded with a drill speed of 5,000 rpm and irrigation. 2. With drill speeds of 800, 3,500, 5,000 rpm and no irrigation, temperatures of surrounding bone rose from $+1.5^{\circ}\;to\;+6.8^{\circ}C$, but maximum temperature was $40^{\circ}C$ at 5,000 rpm. 3. On radiographic examination, bone resorptions were observed at the upper half of implant of 5,000 rpm without irrigation and one case of 5,000 rpm with irrigation. 4. Osseointegration was unsuccessful in cases of 3,500, 5,000 rpm without irrigation due to fibrous connective tissue formation to the outer surface and hollow, but it was successful in a case of 800 rpm without irrigation. 5. Osseointegration was successful in cases of 300, 800, 2,000 and 3,500 rpm with irrigation. But fibrous connective tissue formation was observed at the hollow of implant inserted with 5,000 rpm with irrigation.

• Journal of the Institute of Electronics and Information Engineers
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• v.53 no.5
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• pp.123-131
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• 2016

To capture color and near-infrared images simultaneously, a multi-spectral filter array(MSFA) sensor is used. This is because an NIR band gives additional invisible information to human eyes to see subject under extremely low light level. However, because lenses have different refractive indices for different wavelengths, lenses may fail to focus widely different rays to the same convergence point. This is why a chromatic aberration(CA) problem occurs and images are degraded. In this paper, the image restoration algorithm for an MSFA image, which removes the CA problem, is presented. The obtained MSFA image is filtered by the estimated low-pass kernel to generate a base image. This base image is used to remove CA problem in multi-spectral(MS) images. By modeling the image degradation process and by using the least squares approach of the difference between the high-frequencies of the base and MS images, the desired high-resolution MS images are reconstructed. The experimental results show that the proposed algorithm performs well in estimating the high-quality MS images and reducing the chromatic aberration problem.

• The Journal of Korean Academy of Prosthodontics
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• v.28 no.1
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• pp.7-23
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• 1990

The success or failure of endosseous dental implants is related to the cellular activity at the implant surface. Success seems to be associated with the enclosure of the implant in a non-inflammed connective tissue or the formation of a direct bone implant interface. The purpose of this study was to examine the tissue reactions to the various implants at the submergible state in dog mandible. The $Br\"{a}nemark$, Core-Vent, Intergral, Bone spiral were selected for evaluation and also the Kimplant, Nephrite were used for the experimental study. After 4 months the animals were sacrificed. The interface zone between bone and implant was investigated using x-rays, light microscope, scanning electron microscope, transmission electron microscope. The following results were obtained from this study. 1. $Br\"{a}nemark$, Core-Vent, Kimplant, Integral showed no mobility and bone growth over the healing screws of the implants. Histologically most of the implant surface were covered by remodelled lamellar bone, and partly by a cellular layer or the thin fibrous tissue layer. 2. The Bone spiral showed no mobility and partially radiolucent line around the implant. The upper part of the implant was surrounded by a thin fibrous connective tissue and the middle, apical part of it were contacted with bone directly. 3. The Nephrite implant showed severe mobility and a radiolucent line around the implant. Histologically it showed mild inflammation and was surrounded by a fibrous connective tissue. 4. Scanning electron microscope showed that there was no amorphous ground substance in the Nephrite implant but the formation of ground substance over the collagen filaments in other implants. 5. Transmission electron microscope showed that collagen filaments were approached irregularly to the surface of all implants and in the $Br\"{a}nemark$, Core-Vent, Kimplant, Integral there was amorphous layer between the implant and the collagen filaments. It seemed to be ground substances.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.50 no.6
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• pp.714-720
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• 2017

Exposure to ultraviolet (UV) radiation is associated with the development of adverse effects in skin. Among the three types of UV rays, UV-B causes the most damaging effects, inducing sunburn and penetrating the outer skin, resulting in DNA mutations and skin cancer. The objective of this study was to formulate a UV-protective film by incorporating Ecklonia cava extracts. Cells covered with the film were exposed to UV-B (50, 80, and $100mJ/cm^2$). To determine the protective effects of the film, we evaluated cell viability, intracellular ROS generation, and apoptosis. We found that all E. cava extracts absorbed UV light and exhibited protective effects against UV-B-induced photodamage. Among the protective films examined in this study, that incorporating an E. cava 70% ethanol extract (70EX) formed the most effective protection against UV-B in HaCaT cells. These findings suggest that the application of film containing E. cava extract could prevent UV-B-induced photodamage, and offer protection against the detrimental effects of UV radiation, thus maintaining physiological condition.

• Korean Journal of Rural Living Science
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• v.8 no.2
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• pp.119-124
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• 1997

In this study we tried to give a decision on propriety of working conditions, to present ideas on reducing work loads, and to grope for efficiency of agricultural works. For this we examined the actual working conditions of cultivating welsh onion in the summer ground. And we improved harmful factors that affect farmer's health by considering results of previous study and farmer's subjective sensation. And we measured. compared, and analyzed the farmer's work loads before and after improvement. The results of this study are as follows ; 1. According to examine the actual working conditions of cultivating welsh onion in the summer ground, farmers have experienced physical and mental chronic fatigue on the basis of farmer's appel to eye - fatigue and sun - burned skin on hot working environment including excessive ultraviolet rays, the rough ground condition, inconsistent arrangement of working stand and sorter, heavy - weared habits, and unsuitable working posture. 2. When we improved harmful factors that affect farmer's health, conformed the effects on important work efficiency index such as heart rate, electromyovolume, body temperature, and microclimate inside clothing and work loads were decreased by eliminating the hillock and obstacles of ground, decreasing the clothing weight, using proper clothing appliances such as hat and sunglasses, controlling height of working stand and sorter suitably, improving the working postures and methods as using assistant appliances, alloting the working time and sequence effectively and presenting the light gymnastic exercises and rest for fatigue restoration.

• Journal of Sensor Science and Technology
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• v.24 no.3
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• pp.202-207
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• 2015

As a feasibility study on development of a gamma imaging probe, we developed a scintillating film-based gamma imaging detector that can obtain scintillation images with information of gamma-ray distribution. The scintillating film-based gamma imaging detector was composed of a sensing probe, an image intensifier, and a beam profiler. To detect and transmit scintillation image, the sensing probe was fabricated by coupling a scintillating film, a fiber-optic image conduit, and a fiber-optic taper, consecutively. First, the optical images of USAF 1951 resolution target were obtained and then, modulation transfer function values were calculated to test the image quality of the sensing probe. Second, we measured the scintillation images according to the activity of the 137Cs and the distance between the surface of 137Cs and the distal-end of sensing probe. Finally, the intensities of scintillating light as functions of the activity and the distance were evaluated from the region of interest in the scintillation image. From the results of this study, it is expected that a fiber-optic gamma imaging detector can be developed to detect gamma-rays emitted from radiopharmaceuticals during radioimmunoguided surgery.

• Journal of the Institute of Convergence Signal Processing
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• v.8 no.1
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• pp.78-83
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• 2007

Robot collects surrounding information to recognize tile unknown environment by using various sensors such as visual, infrared ray and ultra sonic sensors. Although visual sensor is the most popular one, it has some difficulties in collecting data in dark or too bright environment due to sensitivity of the light. It also requests significant amount of calculation on collecting data from certain images with marked, straight and curved ones. As an alternative, ultra sonic sensor can simply overcome this visual sensing system's flaw and easily be used. It is easier than visual system, especially in case of collecting data on object and distance in dark environment. Ultra sonic sensor can replace the expensive visual sensing system not only in avoiding obstacles but also in reaching to the target area smoothly. The purpose of this paper is to develop the algorithm to optimize the environmental recognition, path planning and free-ranging by minimizing errors caused by inaccurate information and by considering characteristics of the ultra sonic rays such as refraction and diffusion. This paper also realizes the system that can recognize the environment and make the appropriate path planning by applying the algorithm on this moving robot.