• The Korean Journal of Nuclear Medicine Technology
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• v.17 no.1
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• pp.36-42
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• 2013

Purpose: Recently with CT developed, various studies for reduction of exposure dose is underway. Study of bismuth shields in these studies is actively underway, and has already been applied in the clinical. However, the application of the PET/CT examination was not activated. Therefore, through this study, depending on the application of bismuth shields in the PET/CT examination, we want to identify the quality of the image and the impact on the SUV. Materials and Methods: In this study, to apply to the shielding of the breast, by using the bismuth shields that contains 0.06 mmPb ingredients, was applied to the PET/CT GEMINI TF 64 (Philips Healthcare, Cleveland, USA). Phantom experiments using the NEMA IEC Body Phantom, images were acquired according to the presence or absence of bismuth shields apply. Also, When applying, images were obtained by varying the spacing 0, 1, 2 cm each image set to the interest range in the depth of the phantom by using EBW-NM ver.1.0. Results: When image of the PET Emission acquires, the SUV was in increased depending on the use of bismuth shields, difference in the depth to the surface from deep in the phantom increasingly SUV increased (P<0.005). Also, when using shields, as the more gab decreased, SUV is more increased (P<0.005). Conclusion: Through this study, PET/CT examination by using of bismuth shields which is used as purpose of reduction dose be considered. When using shields, the difference of SUV resulting from the application of bismuth shields exist and that difference is more decreased as gab of shields and surface is wider. Therefore, setting spacing of shield should be considered, if considering the reduction of the variation of SUV and image quality, disease of deep or other organs should be a priority rather than superficial disease. Through this study, when applying identified to clinical examination, the reduction of unnecessary exposure is considered.

• Journal of the Mineralogical Society of Korea
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• v.7 no.1
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• pp.40-48
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• 1994

The weathering of the Namsan granite was studied in terms of sorption process. The Namsan granite consists mainly of quartz, alkali feldspar, plagioclase (${Ab_{85}An_{15}}-Ab_{100}$ and biotite with small amounts of sericite, magnetite and ilmenite. The kinetic factors for altering the granite body are the proton and hydroxyl ions derived from the reaction of water and mineral. There are two different types of pH variation curves for rocks of different mineral assemblages. when powdered granite was dispersed in distilled water under ambient condition. The sorption-process proceeds by three steps for fresh granite; (1) the initial rapid pH-rise to 10 by the uptake of proton by negatively charged mineral surfaces, (2) the gradual pH-down, and (3) the stable pH tail between 7.1-7.5. For somewhat weathered granites, the sorption proceeds; (1) the initial rapid pH-down to 4.8, (2) the slight pH-rise and slow ph-down, and (3) the stable pH tail between 5.0-5.3. The reaction rate is controlled by the density of adsorbable sites, the solubility of the mineral, pH of the system and formation of amorphous gel and gibbsite. Amorphous gel floates on the surface of the solution while stirring the powdered granite and then is transformed into gibbsite in an hour or so. The pH saturation values for -325 mesh fresh granite from 5 m depth is about pH 10 when rock/water ratio is over 10g/200 ml.

• Journal of IKEEE
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• v.24 no.2
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• pp.654-660
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• 2020

Through the output of brain waves during muscle operation, this paper checks whether it is possible to find characteristic vectors of brain waves that are capable of dividing left and right movements by extracting brain waves in specific areas of muscle signal output that include the motion of the left and right muscles or the will of the user within EEG signals, where uncertainties exist considerably. A typical surface EMG and noninvasive brain wave extraction method does not exist to distinguish whether the signal is a motion through the degree of ionization by internal neurotransmitter and the magnitude of electrical conductivity. In the case of joint and motor control through normal robot control systems or electrical signals, signals that can be controlled by the transmission and feedback control of specific signals can be identified. However, the human body lacks evidence to find the exact protocols between the brain and the muscles. Therefore, in this paper, efficiency is verified by utilizing the results of application of CSP (Common Spatial Pattern) filter to verify that the left-hand and right-hand signals can be extracted through brainwave analysis when the subject's behavior is performed. In addition, we propose ways to obtain data through experimental design for verification, to verify the change in results with or without filter application, and to increase the accuracy of the classification.

• Korean Journal of Ecology and Environment
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• v.47 no.3
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• pp.214-218
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• 2014

We introduce a technical equipment of GATe (Green (algae)-tide) water combine developed by K-water. The GATe water combine consists of five modules: main body and buoyant, transfer hopper, screen conveyer, sludge remover, and separator of algae and waste. Also a sprinkler, as the pre-treatment step if necessary, is equipped to the device to spread out environmental-friendly algaecide under the circumstance that the level of algal bloom does not reach to the scum-forming condition. The overall module system of this device is very simple. Based on the field test, the device covers surface area of ca. $500,000m^2day^{-1}$ during the period from May to July, and treats water volume as much as $500,000m^3day^{-1}$ in spite of some variation depending on the water quality condition. The removal efficiency of the device appeared to be over 90%. In addition, the operating duration of the device was able to expand to cover the period between March and November. We expect this new technology can be used to solve algal bloom problems in drinking water resource and public water area.

• Archives of Plastic Surgery
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• v.38 no.4
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• pp.445-450
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• 2011

Purpose: The objective of this study is to analyze the epidemiological characteristics of pediatric burn patients and to determine the targets for a pediatric burn prevention program. Methods: A retrospective review of all medical records of acute pediatric burn patients (age < 15 years old) admitted to our hospital between January 2005 and December 2009 was performed. Results: 1472 males and 1323 females were investigated, with a male to female ratio of 1.11 : 1. The greatest number of burn patients were those with an age of 1~2 years (1,463, 52.3%). Scalding burn was the most common cause of injury, which accounted for 2183 (78.1%) patients, followed by contact burns (10.5%), flame burn (4.9%), steam burn (3.6%). Especially steam burn was the second cause of injury in the age under 1 year, while flame burn was the second cause of injury in the age over 7 years. During recent 5 years, incidence of flame burn, steam burn, electrical burn gradually decreased. Variation of seasonal incidence is minimal and most of the patients (2,716 cases, 97.2%) had burns less than 20% TBSA (Total body surface area). The median hospital stay was 18.79 days, and the rate of operation was 28.6% with a high rate in electrical burn (76.2%), flame burn (50.0%), steam burn (46.1%). 6 patients died in this series, which yielded a mortality rate of 0.2%. Conclusion: Prevention efforts should reflect recent study results. Focused prevention program and campaign to make people aware of risk factors and their avoidance is required to reduce the number of burn accidents in children.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.15 no.1
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• pp.1-25
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• 1982

Limnological study on the physico-chemical properties and biological characteristics of the Lake Ok-Jeong was made from May 1980 to August 1981. For the planktonic organisms in the lake, species composition, seasonal change and diurnal vertical distribution based on the monthly plankton samples were investigated in conjunction with the physico-chemical properties of the body of water in the lake. Analysis of temperature revealed that there were three distinctive periods in terms of vertical mixing of the water column. During the winter season (November-March) the vertical column was completely mixed, and no temperature gradient was observed. In February temperature of the whole column from the surface to the bottom was $3.5^{\circ}C$, which was the minimum value. With seasonal warming in spring, surface water forms thermoclines at the depth of 0-10 m from April to June. In summer (July-October) the surface mixing layer was deepened to form a strong thermocline at the depth of 15-25 m. At this time surface water reached up to $28.2^{\circ}C$ in August, accompanied by a significant increase in the temperature of bottom layer. Maximum bottom temperature was $r5^{\circ}C$ which occurred in September, thus showing that this lake keeps a significant turbulence Aehgh the hypolimnial layer. As autumn cooling proceeded summer stratification was destroyed from the end of October resulting in vertical mixing. In surface layer seasonal changes of pH were within the range from 6.8 in January to 9.0 in guutuost. Thighest value observed in August was mainly due to the photosynthetic activity of the phytoplankton. In the surface layer DO was always saturated throughout the year. Particularly in winter (January-April) the surface water was oversaturated (Max. 15.2 ppm in March). Vertical variation of DO was not remarkable, and bottom water was fairly well oxygenated. Transparency was closely related to the phytoplankton bloom. The highest value (4.6 m) was recorded in February when the primary production was low. During summer transparency decreased hand the lowest value (0.9 m) was recorded in August. It is mainly due to the dense blooming of gnabaena spiroides var. crassa in the surface layer. A. The amount of inorganic matters (Ca, Mg, Fe) reveals that Lake Ok-Jeong is classified as a soft-water lake. The amount of Cl, $NO_3-N$ and COD in 1981 was slightly higher than those in 1980. Heavy metals (Zn, Cu, Pb, Cd and Hg) were not detectable throughout the study period. During the study period 107 species of planktonic organisms representing 72 genera were identified. They include 12 species of Cyanophyta, 19 species of Bacillariophyta, 23 species of Chlorophyta, 14 species of Protozoa, 29 species of Rotifera, 4 species of Cladocera and 6 species of Copepoda. Bimodal blooming of phytoplankton was observed. A large blooming ($1,504\times10^3\;cells/l$ in October) was observed from July to October; a small blooming was present ($236\times10^3\;cells/l$ in February) from January to April. The dominant phytoplankton species include Melosira granulata, Anabaena spiroides, Asterionella gracillima and Microcystis aeruginota, which were classified into three seasonal groups : summer group, winter group and the whole year group. The sumner group includes Melosira granulate and Anabaena spiroides ; the winter group includes Asterionella gracillima and Synedra acus, S. ulna: the whole year group includes Microtystis aeruginosa and Ankistrodesmus falcatus. It is noted that M. granulate tends to aggregate in the bottom layer from January to August. The dominant zooplankters were Thermocpclops taihokuensis, Difflugia corona, Bosmina longirostris, Bosminopsis deitersi, Keratelle quadrata and Asplanchna priodonta. A single peak of zooplankton growth was observed and maximum zooplankton occurrence was present in July. Diurnal vertical migration was revealed by Microcystis aeruginosa, M. incerta, Anabaena spiroides, Melosira granulata, and Bosmina longirostris. Of these, M. granulata descends to the bottom and forms aggregation after sunset. B. longirostris shows fairly typical nocturnal migration. They ascends to the surface after sunset and disperse in the whole water column during night. Foully one species of fish representing 31 genera were collected. Of these 13 species including Pseudoperilnmpus uyekii and Coreoleuciscus splendidus were indigenous species of Korean inland waters. The indicator species of water quality determination include Microcystis aeruginosa, Melosira granulata, Asterionelta gracillima, Brachionus calyciflorus, Filinia longiseta, Conochiloides natans, Asplanchna priodonta, Difflugia corona, Eudorina elegans, Ceratium hirundinella, Bosmina longirostris, Bosminopsis deitersi, Heliodiaptomus kikuchii and Thermocyclops taihokuensis. These species have been known the indicator groups which are commonly found in the eutrophic lakes. Based on these planktonic indicators Lake Ok-Jeong can be classified into an eutrophic lake.

• Progress in Medical Physics
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• v.25 no.3
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• pp.167-175
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• 2014

The purpose of this study is to evaluate the variation of the dose which is delivered to the patients with glottis cancer under IMRT (intensity modulated radiation therapy) by using the 3D registration with CBCT (cone beam CT) images and the DIR (deformable image registration) techniques. The CBCT images which were obtained at a one-week interval were reconstructed by using B-spline algorithm in DIR system, and doses were recalculated based on the newly obtained CBCT images. The dose distributions to the tumor and the critical organs were compared with reference. For the change of volume depending on weight at 3 to 5 weeks, there was increased of 1.38~2.04 kg on average. For the body surface depending on weight, there was decreased of 2.1 mm. The dose with transmitted to the carotid since three weeks was increased compared be more than 8.76% planned, and the thyroid gland was decreased to 26.4%. For the physical evaluation factors of the tumor, PITV, TCI, rDHI, mDHI, and CN were decreased to 4.32%, 5.78%, 44.54%, 12.32%, and 7.11%, respectively. Moreover, $D_{max}$, $D_{mean}$, $V_{67.50}$, and $D_{95}$ for PTV were increased or decreased to 2.99%, 1.52%, 5.78%, and 11.94%, respectively. Although there was no change of volume depending on weight, the change of body types occurred, and IMRT with the narrow composure margin sensitively responded to such a changing. For the glottis IMRT, the patient's weight changes should be observed and recorded to evaluate the actual dose distribution by using the DIR techniques, and more the adaptive treatment planning during the treatment course is needed to deliver the accurate dose to the patients.

• The Journal of Korean Academy of Prosthodontics
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• v.40 no.1
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• pp.1-17
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• 2002

The purpose of this study is to examine the possibility of thermal injury to bone tissues during an implant site preparation under the same condition as a typical clinical practice of $Br{\aa}nemark$ implant system. All the burs for $Br{\aa}nemark$ implant system were studied except the round bur The experiments involved 880 drilling cases : 50 cases for each of the 5 steps of NP, 5 steps of RP, and 7 steps of WP, all including srew tap, and 30 cases of 2mm twist drill. For precision drilling, a precision handpiece restraining system was developed (Eungyong Machinery Co., Korea). The system kept the drill parallel to the drilling path and allowed horizontal adjustment of the drill with as little as $1{\mu}m$ increment. The thermocouple insertion hole. that is 0.9mm in diameter and 8mm in depth, was prepared 0.2mm away from the tapping bur the last drilling step. The temperatures due to countersink, pilot drill, and other drills were measured at the surface of the bone, at the depths of 4mm and 8mm respectively. Countersink drilling temperature was measured by attaching the tip of a thermocouple at the rim of the countersink. To assure temperature measurement at the desired depths, 'bent-thermocouples' with their tips of 4 and 8mm bent at $120^{\circ}$ were used. The profiles of temperature variation were recorded continuously at one second interval using a thermometer with memory function (Fluke Co. U.S.A.) and 0.7mm thermocouples (Omega Co., U.S.A.). To simulate typical clinical conditions, 35mm square samples of bovine scapular bone were utilized. The samples were approximately 20mm thick with the cortical thickness on the drilling side ranging from 1 to 2mm. A sample was placed in a container of saline solution so that its lower half is submerged into the solution and the upper half exposed to the room air, which averaged $24.9^{\circ}C$. The temperature of the saline solution was maintained at $36.5^{\circ}C$ using an electric heater (J. O Tech Co., Korea). This experimental condition was similar to that of a patient s opened mouth. The study revealed that a 2mm twist drill required greatest attention. As a guide drill, a twist drill is required to bore through a 'virgin bone,' rather than merely enlarging an already drilled hole as is the case with other drills. This typically generates greater amount of heat. Furthermore, one tends to apply a greater pressure to overcome drilling difficulty, thus producing even greater amount heat. 150 experiments were conducted for 2mm twist drill. For 140 cases, drill pressure of 750g was sufficient, and 10 cases required additional 500 or 100g of drilling pressure. In case of the former. 3 of the 140 cases produced the temperature greater than $47^{\circ}C$, the threshold temperature of degeneration of bone tissue (1983. Eriksson et al.) which is also the reference temperature in this study. In each of the 10 cases requiring extra pressure, the temperature exceeded the reference temperature. More significantly, a surge of heat was observed in each of these cases This observations led to addtional 20 drilling experiments on dense bones. For 10 of these cases, the pressure of 1,250g was applied. For the other 10, 1.750g were applied. In each of these cases, it was also observed that the temperature rose abruptly far above the thresh old temperature of $47^{\circ}C$, sometimes even to 70 or $80^{\circ}C$. It was also observed that the increased drilling pressure influenced the shortening of drilling time more than the rise of drilling temperature. This suggests the desirability of clinically reconsidering application of extra pressures to prevent possible injury to bone tissues. An analysis of these two extra pressure groups of 1,250g and 1,750g revealed that the t-statistics for reduced amount of drilling time due to extra pressure and increased peak temperature due to the same were 10.80 and 2.08 respectively suggesting that drilling time was more influenced than temperature. All the subsequent drillings after the drilling with a 2mm twist drill did not produce excessive heat, i.e. the heat generation is at the same or below the body temperature level. Some of screw tap, pilot, and countersink showed negative correlation coefficients between the generated heat and the drilling time. indicating the more the drilling time, the lower the temperature. The study also revealed that the drilling time was increased as a function of frequency of the use of the drill. Under the drilling pressure of 750g, it was revealed that the drilling time for an old twist drill that has already drilled 40 times was 4.5 times longer than a new drill The measurement was taken for the first 10 drillings of a new drill and 10 drillings of an old drill that has already been used for 40 drillings. 'Test Statistics' of small samples t-test was 3.49, confirming that the used twist drills require longer drilling time than new ones. On the other hand, it was revealed that there was no significant difference in drilling temperature between the new drill and the old twist drill. Finally, the following conclusions were reached from this study : 1 Used drilling bur causes almost no change in drilling temperature but increase in drilling time through 50 drillings under the manufacturer-recommended cooling conditions and the drilling pressure of 750g. 2. The heat that is generated through drilling mattered only in the case of 2mm twist drills, the first drill to be used in bone drilling process for all the other drills there is no significant problem. 3. If the drilling pressure is increased when a 2mm twist drill reaches a dense bone, the temperature rises abruptly even under the manufacturer-recommended cooling conditions. 4. Drilling heat was the highest at the final moment of the drilling process.