• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.05a
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• pp.112-112
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• 2004

양전자 단층촬영(PETㆍ Positron Emission Tomography)에 가장 널리 사용되는 방사성의약품인 FDG는 방사성동위원소인$^{18}$ F가 사용되며, 이는 안정물질인 H$_2$$^{18}$ O을 액체표적에 주입한 후, 고 에너지의 양성자빔을 조사하여 생산한다. 표적은 내화학성 및 높은 인장강도론 가진 재질인 titanium으로 제조하며, 0.075mm의 얇은 박판이 양성자빔 입사부에 사용된다. H$_2$$^{18}$ O가 주입된 표적에 양성자빔이 입사되는 순간 표적 내부는 높은 에너지로 인하여 표적물은 고온상태로 기화가 일어나고 이것이 압력을 증가시켜 target window는 바깥쪽으로 팽창한다.(중략)

• Journal of Energy Engineering
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• v.10 no.3
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• pp.294-298
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• 2001

A research for transmutation reactor is in progress to transmute high radioactive isotopes into low radioactive ones. In this study, thermal-hydraulic and structural analysis was performed to design liquid metal target system that would be used in subcritical transmutation reactor. Diffuse plate installation was considered to enhance cooling of window. And thermal-structural analysis of window was performed varying window thickness, beam power, and coolant flow rate to determine target system design valuers. It is ensured that maximum window temperature and stress would be acceptable in the design condition.

• The Journal of the Korea Contents Association
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• v.18 no.11
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• pp.484-492
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• 2018

This study examined the effects of field complexity and type of target objects on the performance in baggage screening task. A total of 62 participants(male: 45.2%, female: 54.8%) participated and their mean age was 22.88. The simulated baggage screening task was developed for this study and after the orientation and task exercises, main experiment session was conducted. Participants performed a total of 200 tasks and 40(20%) contained target object. The complexity was set at three levels: high, middle, and low levels and the number of background items contained 20, 14. and 8 respectively. The type of target was set as gun, knife, liquid, and righter. The dependent variables were hit ratio and reaction time. The results showed that the hit ratio decreased and reaction time increased significantly as field complexity increased, and they varied depending on the type of target. The hit ratio of the knife was the highest and liquid lowest and reaction time of the knife was the fastest and liquid slowest. In addition, the interaction effect was also significant. Knife was not affected by complexity, however, small item such as lighter was most affected by complexity.

• Journal of the Korean Institute of Gas
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• v.20 no.2
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• pp.35-42
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• 2016

Formamide is a colorless fluid with ammonia odor, and irritable when inhaled. It has $LD_{50}$ value of > 5,577 mg/kg in rats for acute oral toxicity and NOAEL of 113 mg/kg/day for target organ (liver) of whole body toxicity. It is also known as reproductive toxicant (1B) and TWA(Time Weighted Average) for it is 10 ppm. Workplace measurements of work places dealing with formamide showed the ppm of all 25 samples was very lower than WEL. However, the exposure concentration can change, depending on workplace condition such as the intensity of work, operating local ventilation system, and wearing protection equipment (Respirators). Therefore, considering it with the risk of whole body toxicity and reproductive toxicity, exposure quantity of each imaginary scenario was calculated at 5.16, 1.72, and $0.43mg/m^3$. The average value was calculated at 0.02-0.58, 0.02-0.66 at 90 percent of cumulative distribution, 0.02-0.69 at 95 percent of cumulative distribution. Therefore, it was generally evaluated to be safe because all values were below 1. However, caution is required to prevent health hazard because it has hepatotoxicity and reproductive toxicity and risk of a high level momentary exposure, depending on the condition of workplace.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.2
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• pp.1200-1206
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• 2015

The major target for drug discovery, G-protein coupled receptor (GPCR) is involved in many physiological activities and related to various diseases and disorders. Among experimental techniques relating to the GPCR drug discovery process, various cell-based screening methods are influenced by cell conditions used in the overall process. Recently, the utilization of frozen cells is suggested in terms of reducing data variation and cost-effectiveness. The aim of this study is to evaluate various conditions in cell freezing such as temperature conditions and storage terms. The stable cell lines for calcium sensing receptor and urotensin receptor were established followed by storing cultured cells at $-80^{\circ}C$ up to 4 weeks. To compare with cell stored at liquid nitrogen, agonist and antagonist responses were recorded based on the luminescence detection by the calcium induced photoprotein activation. Cell signals were reduced as the storage period was increased without the changes in $EC_{50}$ and $IC_{50}$ values $EC_{50}:3.46{\pm}1.36mM$, $IC_{50}:0.49{\pm}0.15{\mu}M$). In case of cells stored in liquid nitrogen, cell responses were decreased comparing to those in live cells, however changes by storage periods and significant variations of $EC_{50}/IC_{50}$ values were not detected. The decrease of cell signals in various frozen cells may be due to the increase of cell damages. From these results, the best way for a long-term cryopreservation is the use of liquid nitrogen condition, and for the purpose of short-term storage within a month, $-80^{\circ}C$ storage condition can be possible to adopt. As a conclusion, the active implementation of frozen cells may contribute to decrease variations of experimental data during the initial cell-based screening process.

• Progress in Medical Physics
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• v.17 no.1
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• pp.24-31
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• 2006

Automated analysis software was developed to measure the magnitude of the intrafractional and interfractional errors during breast radiation treatments. Error analysis results are important for determining suitable planning target volumes (PTV) prior to Implementing breast-conserving 3-D conformal radiation treatment (CRT). The electrical portal imaging device (EPID) used for this study was a Portal Vision LC250 liquid-filled ionization detector (fast frame-averaging mode, 1.4 frames per second, 256X256 pixels). Twelve patients were imaged for a minimum of 7 treatment days. During each treatment day, an average of 8 to 9 images per field were acquired (dose rate of 400 MU/minute). We developed automated image analysis software to quantitatively analyze 2,931 images (encompassing 720 measurements). Standard deviations ($\sigma$) of intrafractional (breathing motion) and intefractional (setup uncertainty) errors were calculated. The PTV margin to include the clinical target volume (CTV) with 95% confidence level was calculated as $2\;(1.96\;{\sigma})$. To compensate for intra-fractional error (mainly due to breathing motion) the required PTV margin ranged from 2 mm to 4 mm. However, PTV margins compensating for intefractional error ranged from 7 mm to 31 mm. The total average error observed for 12 patients was 17 mm. The intefractional setup error ranged from 2 to 15 times larger than intrafractional errors associated with breathing motion. Prior to 3-D conformal radiation treatment or IMRT breast treatment, the magnitude of setup errors must be measured and properly incorporated into the PTV. To reduce large PTVs for breast IMRT or 3-D CRT, an image-guided system would be extremely valuable, if not required. EPID systems should incorporate automated analysis software as described in this report to process and take advantage of the large numbers of EPID images available for error analysis which will help Individual clinics arrive at an appropriate PTV for their practice. Such systems can also provide valuable patient monitoring information with minimal effort.