• Fisheries and Aquatic Sciences
• /
• 제12권4호
• /
• pp.324-330
• /
• 2009

Cadmium (Cd) accumulation and elimination were assessed in the tissues of the clam R. philippinarum at four experimental concentrations (control, 10, 20, 100, and $200\;{\mu}g/L$) over an exposure period of 2 weeks and an elimination period of 1 week. Cd accumulated in the digestive gland, gill, and residual clam tissues, and accumulation increased with time of exposure and concentration (100 and $200\;{\mu}g/L$). After 2 weeks of Cd exposure, the order of Cd accumulation in tissues was gill > digestive gland > residual tissues. An inverse relationship was observed between concentration factor (CF) and exposure level, but the CF showed an increase with exposure time. During the depuration period, Cd concentrations in the digestive gland, gill, and residual tissues decreased immediately on the cessation of exposure, except in individuals at the $200\;{\mu}g/L$ concentration. The Cd elimination rate from tissues decreased in the order of digestive gland > gill > residual tissues during the depuration period.

• 대한방사선기술학회지:방사선기술과학
• /
• 제41권6호
• /
• pp.603-610
• /
• 2018

This study examined the following: accuracy of the exposure conditions in the inverter device and three-phase device; output waveform over the exposure conditions; and average and standard deviation of the output waveform. After assessing whether the dose corresponding to the theoretical dose was presented, the following conclusions were obtained: 1. The accuracy of the tube voltage(kVp) and tube current(mA) exposure time(sec) was within the tolerable level prescribed in Korea's Safety Management Standards. In the error, Inverter device was large the tube voltage and exposure time, the three-phase device was large the tube current. 2. In terms of the output waveform of the exposure conditions and the average and standard deviation of the output waveform, the higher tube voltage and larger tube current resulted in greater standard deviation in pulsation. Moreover, the standard deviation of pulsation was shown to be greater in the inverter device than the three-phase device; there was also greater standard deviation in the inverter device considering the exposure time. 3. Regarding the exposure conditions over the output dose, all linearity showed the coefficient of variation which had an allowable limit of error within 0.05. Although the output dose ratio for the inverter device was 1.00~1.10 times no difference that of the three-phase device, there was almost no difference in dose ratio between the tube currents.

• 한국환경보건학회지
• /
• 제37권4호
• /
• pp.235-236
• /
• 2011

• 월간산업보건
• /
• 통권91호
• /
• pp.37-39
• /
• 1995

• 대한방사선협회지
• /
• 제25권1호
• /
• pp.24-24
• /
• 1999

In order to establish reasonable concept and background on repititive films, we analyzed factors due to wasted films grouping into three major factors as 1) artificial factor from exposure and positioning. 2) mechanical factor as mechanic error and jammin

• 한국콘텐츠학회논문지
• /
• 제20권10호
• /
• pp.1-13
• /
• 2020

CMOS 카메라 영상의 화질을 좌우하는 것은 여러 가지가 있는데 그 중에서 영상 노출시간은 중요한 요소이다. 영상 노출시간이 길게 되면 화면 전체 영상이 밝아지게 되고 노출시간이 짧아지면 전체 영상이 어두워지게 된다. 정지 피사체를 사진 촬영할 경우 자동노출 시스템이 적절한 노출시간을 얻는데 충분한 시간이 주어지기 때문에 실시간성이 요구되지 않는다. 하지만 주행 중인 자동차의 블랙박스 같이 주변 빛 환경이 빠르게 변하게 되면 이에 맞추어서 노출시간도 실시간으로 반응하여 적용되어야 한다. 이를 위해서는 실시간성과 주변 빛 환경에 대하여 강건한 자동노출 시스템이 요구된다. 본 논문에서는 ZYNQ의 로직과 ARM코어를 적용한 임베디드 시스템 설계로 병렬 연산처리 가능한 실시간 제어 시스템을 설계하였고 이를 바탕으로 PID 제어를 통해서 66ms 이내에 원하는 목표 값으로 수렴하고 노이즈에 강건한 실시간 CMOS 자동 노출 시스템을 개발하였다.

• 한국환경보건학회지
• /
• 제44권6호
• /
• pp.556-562
• /
• 2018

Objectives: This study was conducted to investigate the boron concentrations in 30 slime products and estimate children's dermal exposure to boron. Methods: Thirty slime products from online and offline stores were purchased for boron analysis. The boron content of each slime sample was analyzed using ICP-OES. A nationwide survey was performed to determine use patterns of slimes by a home-visit survey of 10,000 children divided into three age groups: 0-2, 3-6, and 7-12 years. The dermal exposure to boron was calculated using an exposure algorithm for child slime users. Results: The proportion of the child population using slime was 45.8%, and the mean use frequency was $2.5{\pm}3.8$ per week (range: 0.08-35). Mean time spent playing with slime was $19.6{\pm}11.3min$ (range: 1-100). Twenty-five of the thirty slimes contained a boron concentration exceeding the EU limit for toys made with sticky material of 300 mg/kg. Dermal exposure ranged from $0.0008-13.78{\mu}g/kg/day$ with the maximum weight fractions of boron in the 30 products. The dermal exposure estimate was the highest in 7-12 years old group. Conclusion: Slime use among Korean children may cause high exposure to boron. Regulation is needed to minimize boron exposure from slime products.

• Imaging Science in Dentistry
• /
• 제35권1호
• /
• pp.33-40
• /
• 2005

Purpose : (1) To analyse the effect of exposure time, ROI size and one impact factor in the image processing procedure on estimates of fractal dimension; and (2) to analyse the correlated relationship between the fractal dimension and the Cu-Eq value (bone density). Materials and Methods : The cylindric bone phantoms of 6 large and 5 small diameter having different bone densities respectively and human dry mandible segment with copper step wedge were radiographed at 1.0 and 1.2 sec esposure (70 kVp, 7 mA) using one occlusal film and digitized. Eleven rectangular ROIs from 11 cylindric bone phantoms and 4 rectan-gular ROIs from cortical, middle, periodontal regions, and socket of bone were selected. Gaussian blurred Image was subtracted from original image of each ROI and multiplied respectively by 1, 0.8, and 0.5, and then the image was made binary, eroded and dilated once, and skeletonized. The fractal dimension was calculated by means of a box counting method in the software ImageJ. Results : The fractal dimension was decreased gradually with continued bone density decrease showing strong correlations (bone phantom; r> 0.87, bone; r> 0.68) under 70 kVp 1.0 sec M = 0.8. Fractal dimensions showed the significant differerence (p < 0.05) between two different exposure times on the same small ROI of bone phantom. Fractal dimensions between two different sizes of ROI on bone phantom showed the significant differerence (p < 0.05) under 1.2 sec exposure, but did not show it (p > 0.05) under 1.0 sec exposure. Conclusions : Exposure time, ROI size, and modifying factor during subtracting could become impacting on the results of fractal dimension. Fractal analysis with thoroughly evaluated method considering the various impacting factors on the results could be useful in assessing the bone density in dental radiography.

• The Korean Journal of Physiology
• /
• 제29권1호
• /
• pp.1-11
• /
• 1995

Alveolar macrophages play a pivotal role in the pathogenesis of silicosis since the macrophages may release a wide variety of toxic and inflammatory mediators as well as mitogenic growth factors. In the present study, the effects of in vitro exposure to silica on release of various mediator such as reactive oxygen species, platelet activating factor(PAF), and interleukin-1 (IL-1) by alveolar macrophages were examined. First, hydrogen peroxide release from alveolar macrophages was monitored by measuring the change in fluorescence of scopoletin in the absence or presence of graded concentration of silica. Significantly enhanced release of hydrogen peroxide was observed at 0.5 mg/ml and above. A maximal enhancement of 10 fold above control was observed at 5 mg/ml silica. Similarly, in vitro exposure to silica also significantly stimulated the generation of chemiluminescence from alveolar macrophages at 0.5 mg/ml and above with n maximal enhancement of 8 fold at 5 mg/ml silica. Second, PAF release from alveolar macrophages after 30 min incubation at $37^{\circ}C$ in absence or presence of zymosan and silica was determined by measuring $^{3}H-serotonin$ release ability of the conditioned macrophage supernates from platelets. 5 mg/ml zymosan as a positive control fur the PAF assay increased PAF release by 19 % of total serotonin release. Furthermore, silica also resulted in significant enhancement of the PAF release compared with that in unstimulated (control) cells, i.e., $17.7{\pm}5.8%$ and $24.0{\pm}4.9%$ of total serotonin release at 5 mg/ml and 10 mg/ml silica, respectively, which represents the release of nanomole levels of PAF. Lastly, IL-1 production by alveolar macrophages was analysed following their stimulation with lipopolysaccharide (LPS) and silica by their capacity to stimulate thymocyte proliferation. $10\;{\mu}g/ml$ LPS resulted in an 11 fold increase in IL-1 production. In comparison, $50\;{\mu}g/ml$ silica resulted in a 4 fold increase in IL-1 release. These data indicate that in vitro exposure of alveolar macrophages to silica activates the release of various bioactive mediators such as reactive oxygen species, PAF and IL-1 which thus contribute to amplification of inflammatory reactions and regulation of fibrotic responses by the lung after inhalation of silica.

• 대한방사선기술학회지:방사선기술과학
• /
• 제21권1호
• /
• pp.29-34
• /
• 1998

The purpose of simple abdomen erect projection is to see the fluid level which indicates gastrointestinal ileus or free air due to perforation. we do not have to insist on low kVp technique in simple abdomen erect position as long as we can detect the fluid level and free air shadow. Therefore, the author tried to decrease patient dose by high kVp technique and to improve the image quality due to motion artifact by reduction of exposure time. [Methods] Experiment 1. * screen/film SRO1000/HRH * exposure factor : $140\;kvp{\pm}5\;kv$ with added filters, 200 mA, 0.01 sec * phantom : Acryles : 15.0 cm(equivalent to 17 cm body thickness) 17.5 cm(equivalent to 21 cm body thickness) 20.0 cm (equivalent to 25 cm body thickness) With the exposure factor for same film density($D=0.8{\pm}0.1$) and with the materials above, we tried to find out entrance skin dose and gonad dose for both male and female. Experiment 2. Burger's phantom radiography were checked to see whether there was any change of image quality according to the kVp and the added filters. Experiment 3. Using rotating meter(self made), we examined the motion artifact and the exposure time limitation. [Results and conculution] 1. Using high voltage technique of 140 kVp with added filter, Skin dose, testicle dose and ovary dose decrease to 89.3%, 47% and 71.4% respectively compare to 70 kVp technique, 2. No great changes of Burger's phantom image has detected as from 70 kVp to 140 kVp and the air hole size of Burger's phantom over 0.028 cc(Diameter 3 mm, hight 4 mm) can be distinghished. 3. 0.01 sec(1 pulse) exposure time is possible in the single phase full wave rectification that why we can quitely reduce the unsharness caused by patient's movement.