• 대한방사선기술학회지:방사선기술과학
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• 제45권5호
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• pp.449-455
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• 2022

This study is to present a Geant4 code for the simulation of the absorbed dose distribution given by a medical linac for 6 MV photon beam. The dose distribution was verified by comparison with calculated beam data and beam data measured in water phantom. They were performed for percentage depth dose(PDD) and beam profile of cross-plane for two field sizes of 10 × 10 and 15 × 15 cm². Deviations of a percentage and distance were obtained. In energy spectrum, the mean energy was 1.69 MeV. Results were in agreement with PDD and beam profile of the phantom with a tolerance limit. The differences in the central beam axis data 𝜹₁ for PDD had been less than 2% and in the build up region, these differences increased up to 4.40% for 10 cm square field. The maximum differences of 𝜹₂ for beam profile were calculated with a result of 4.35% and 5.32% for 10 cm, 15 cm square fields, respectively. It can be observed that the difference was below 4% in 𝜹₃ and 𝜹₄. For two field sizes of 𝜹_50-90 and RW₅₀, the results agreed to within 2 mm. The results of the t-test showed that no statistically significant differences were found between the data for PDD of 𝜹₁, p>0.05. A significant difference on PDD was observed for field sizes of 10 × 10 cm², p=0.041. No significant differences were found in the beam profile of 𝜹₃, 𝜹₄, RW₅₀, and 𝜹_50-90. Significant differences on beam profile of 𝜹₂ were observed for field sizes of 10 × 10 cm², p=0.025 and for 15 × 15 cm², p=0.037. This work described the development and reproducibility of Geant4 code for verification of dose distribution.

• 한국재료학회지
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• 제22권9호
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• pp.489-493
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• 2012

Green phosphors $K_2BaW_2O_8:Tb^{3+}$(1.0 mol%) were synthesized by solid state reaction method. Differential thermal analysis was applied to trace the reaction processes. Three endothermic values of 95, 706, and $1055^{\circ}C$ correspond to the loss of absorbed water, the release of carbon dioxide, and the beginning of the melting point, respectively. The phase purity of the powders was examined using powder X-ray diffraction(XRD). Two strong excitation bands in the wavelength region of 200-310 nm were found to be due to the ${WO_4}^{2-}$ exciton transition and the 4f-5d transition of $Tb^{3+}$ in $K_2BaW_2O_8$. The excitation spectrum presents several lines in the range of 310-380 nm; these are assigned to the 4f-4f transitions of the $Tb^{3+}$ ion. The strong emission line at around 550 nm, due to the $^5D_4{\rightarrow}^7F_5$ transition, is observed together with weak lines of the $^5D_4{\rightarrow}^7F_J$(J = 3, 4, and 6) transitions. A broad emission band peaking at 530 nm is observed at 10 K, while it disappears at room temperature. The decay times of $Tb^{3+}$ $^5D_4{\rightarrow}^7F_5$ emission are estimated to be 4.8 and 1.4 ms, respectively, at 10 and 295 K; those of the ${WO_4}^{2-}$ exciton emissions are 22 and 0.92 ${\mu}s$ at 10 and 200 K, respectively.

• 한국전기전자재료학회논문지
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• 제17권3호
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• pp.323-328
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• 2004

Down-conversion of Eu$^{3+}$ doped LiGdF$_4$ (LGF) for increasing the cell efficiency on dye-sensitized Ti $O_2$ solar cells has been studied. The dye sensitized solar cell (DSC) consisting of mesoporous Ti $O_2$ electrode deposited on transparent substrate, an electrolyte containing I$^{[-10]}$ /I$_3$$^{[-10]}$ redox couple, and Pt counter electrode is a promising alternative to the inorganic solar cell. The structure of DSC is basically a sandwich type, viz., FTO glass/Ru-red dye-absorbed Ti $O_2$/iodine electrolyte/sputtered Pt/FTO glass. The cell without down converter had open circuit potential of approximately 0.66 Volt, the short circuit photocurrent density of 1.632 mA/$\textrm{cm}^2$, and fill factor of about 50 ％ at the excitation wavelength of 550 nm. In addition, 5.6 mW/$\textrm{cm}^2$ incident light intensity beam was used as a light source. From this result, the calculated monochromatic efficiency at the wavelength of 550 nm of this cell was about 9.62 ％. The incident photon to current conversion efficiency (IPCE) of N3 used as a dye in this work is about 80 ％ at around 590 nm and 610 nm, which is the emission spectrum of Eu$^{3+}$ doped LGF, results in efficiency increasing of DSC.C.

• Biomolecules & Therapeutics
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• 제22권4호
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• pp.301-307
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• 2014

Fucodiphlorethol G (6'-[2,4-dihydroxy-6-(2,4,6-trihydroxyphenoxy)phenoxy]biphenyl-2,2',4,4',6-pentol) is a compound purified from Ecklonia cava, a brown alga that is widely distributed offshore of Jeju Island. This study investigated the protective effects of fucodiphlorethol G against oxidative damage-mediated apoptosis induced by ultraviolet B (UVB) irradiation. Fucodiphlorethol G attenuated the generation of 2, 2-diphenyl-1-picrylhydrazyl radicals and intracellular reactive oxygen species in response to UVB irradiation. Fucodiphlorethol G suppressed the inhibition of human keratinocyte growth by UVB irradiation. Additionally, the wavelength of light absorbed by fucodiphlorethol G was close to the UVB spectrum. Fucodiphlorethol G reduced UVB radiation-induced 8-isoprostane generation and DNA fragmentation in human keratinocytes. Moreover, fucodiphlorethol G reduced UVB radiation-induced loss of mitochondrial membrane potential, generation of apoptotic cells, and active caspase-9 expression. Taken together, fucodiphlorethol G protected human keratinocytes against UVB radiation-induced cell damage and apoptosis by absorbing UVB radiation and scavenging reactive oxygen species.

• 비파괴검사학회지
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• 제32권4호
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• pp.401-409
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• 2012

초음파 시험은 접착계면에서 발생하는 미접착 결함을 검출할 수 있는 다른 비파괴 시험보다 미접착 검출 능력이 월등히 뛰어나다. 하지만, 스틸 연소관, 내열 고무, 라이너 및 추진제로 구성된 고체 추진기관은 각 재질의 음향 임피던스의 큰 차이와 반사파의 중첩 때문에 초음파 신호를 분석하기에는 많은 어려움 있다. 그러므로 고체 추진기관의 미접착 결함을 검출하기 위한 초음파 시험은 자동화된 C-Scan 시스템을 이용하여 스틸 연소관과 내열 고무 계면의 극히 제한된 영역에서 적용되어 왔다. 기존의 초음파 시험은 대부분의 초음파가 음향 임피던스가 낮은 고무 재질에서 흡수되므로 고체 추진기관의 라이너와 추진제 사이의 미접착 결함을 검출할 수 없었고, 이런 문제점을 해결하기 위하여 초음파 공진법을 사용하여 주파수 스펙트럼으로부터 공진 주파수를 분석하였다. 본 논문은 초음파 공진 특성을 이용하여 라이너와 추진제 사이의 미접착 결함을 검출할 수 있는 기법에 대해 자세히 기술하였다.

• Biomolecules & Therapeutics
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• 제15권3호
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• pp.182-186
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• 2007

Cefixime is an orally absorbed cephalosporin with a broad spectrum of activity against Gram-negative bacteria and is highly resistant to beta-lactamase degradation. The purpose of the present study was to evaluate the bioequivalence of two cefixime capsules, Suprax capsule (Dong-A Pharmaceutical Co., reference drug) and Alpha-Cefixime capsule (Alpha Pharmaceutical Co., test drug), according to the guidelines of Korea Food and Drug Administration (KFDA). Twenty-four normal subjects, $23.5{\pm}3.72$ years in age and $68.3{\pm}8.89$ kg in body weight, were divided into two groups and a randomized $2{\times}2$ cross-over study was employed. There was one week washout period between the doses. After one capsule containing 100 mg of cefixime was orally administered, plasma was taken at predetermined time intervals and the concentrations of cefixime in plasma were determined using HPLC with UV detector. The pharmacokinetic parameters such as $AUC_{t}$, $C_{max}$ and $T_{max}$ were calculated and ANOVA test was utilized for the statistical analysis of the parameters. The results showed that the differences in $AUC_{t}$, $C_{max}$ and $T_{max}$ between two products were -3.91%, -2.23% and -3.18%, respectively, when calculated against the reference drug. The 90% confidence intervals using logarithmically transformed data were within the acceptance range of $log0.8{\leq}{\delta}{\leq}log1.25$ (e.g., $log0.8786{\leq}{\delta}{\leq}log1.0523$ and $log0.8889{\leq}{\delta}{\leq}log1.0512$ for $AUC_{t}$ and $C_{max}$, respectively). The 90% confidence intervals using untransformed data was within ${\pm}20%$(e.g., $-10.37%{\leq}{\delta}{\leq}6.73%$ for $T_{max}$). All parameters met the criteria of KFDA for bioequivalence, indicating that Alpha-Cefixime capsule (Alpha Pharmaceutical Co.) is bioequivalent to Suprax capsule (Dong-A Pharmaceutical Co.).

• 한국운동역학회지
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• 제16권2호
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• pp.25-35
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• 2006

The purpose of this study was to investigate the shock attenuation mechanisms while varying the loads in a backpack during drop landing. Ten subjects (age: $22.8{\pm}3.6$, height: $173.5{\pm}4.3$, weight: $70.4{\pm}5.2$) performed drop landing under five varying loads (0, 5kg. 10kg. 20kg. 30kg). By employing two cameras (Sony VX2100) the following kinematic variables (phase time, joint rotational angle and velocity of ankle, knee and hip) were calculated by applying 2D motion analysis. Additional data, i.e. max vertical ground force (VGRF) and acceleration, was acquired by using two AMTI Force plates and a Noraxon Inline Accelerometer Sensor. Through analysing the power spectrum density (PSD), drop landing patterns were classified into four groups and each group was discovered to have a different shock attenuation mechanism. The first pattern that appeared at landing was that the right leg absorbed most of the shock attenuation. The second pattern to appear was that subject quickly transferred the load from the right leg to the left leg as quickly as possible. Thus, this illustrated that two shock attenuation mechanisms occurred during drop landing under varying load conditions.

• 약학회지
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• 제46권4호
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• pp.290-294
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• 2002

Cephradine is an orally absorbed cephalosporin with a broad spectrum of activity against gram-positive and gram-negative bacteria and is highly resistant to beta-lactamase degradation. The purpose of the present study was to evaluate the bioequivalence of two cephradine capules, Cephradine capsule (Donggu Pharmaceutical Co., reference drug) and Cephradine capsule (Shinpoong Pharmaceutical Co., test drug), according to the guidelines of Korea Food and Drug Administration. Twenty-six normal volunteers, 24.6 $\pm$ 3.70 years in age and 62.4 $\pm$ 8.99 kg in body weight, were divided into two groups and a randomized 2 $\times$ 2 cross-over study was employed. After one capsule containing 250 mg of cephrdine was orally administered, blood was taken at predetermined time intervals and the concentrations of cephrdine in serum were determined using HPLC with UV detector. The pharmacokinetic parameters such as AU $C_{t}$ to $C_{max}$ and $T_{max}$ were calculated and ANOVA test was utilized for the statistical analysis of the parameters. The results showed that the differences in AUCt, $C_{max}$ and $T_{max}$ between two products were 2.89％, 1.05％ and 1.06％, respectively, when calculated against the reference drug. The 90％ confidence intervals were within log0.8 $\leq$ $\delta$ $\leq$ log1.25 (e.g., log0.9803 $\leq$ $\delta$ $\leq$ log1.0734 and log0.9674 $\leq$ $\delta$ $\leq$ log1.220 for AU $C_{t}$, and $C_{max}$, respectively). Two parameters met the criteria of KFDA for bioequivalence, indicating that Cephradine capsules (Shinpoong Pharmaceutical Co.) is bioequivalent to Cephradine capsules (Donggu Pharmaceutical Co.).o.).o.).).o.).

• Nuclear Engineering and Technology
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• 제2권2호
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• pp.85-95
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• 1970

두개의 threshold detector로서 인자로의 폭발사고시에 방출되는 속 중성자의 속도분포를 측정하고 그로부터 속 중성자의 인체흡수선량을 계산하였다. 이때 속 중성자의 속도분포는 하나의 스펙트럼 매개변수에 의하여 결정된다는 가정으로부터 얻어지는데 이 매개변수는 threshold detector의 반응율을 측정하므로서 구해진다. 속 중성자의 인체흡수선량은 속 중성자의 속도분포 변화에 따라 큰 변동이 없었으나 threshold detector의 평균반응단면적은 크게 변하였다. 따라서 속 중성자의 속도분포에 관계없이 threshold detector의 평균반응단면적을 고정된 값으로 취하여 속 중성자선량을 계산한다면 큰 오차를 일으키게 될 것이라는 것을 보여주었다. 한편 핵분열에서 방출되는 속 중성자의 속도분포에 대한 세 해석적 표현인 즉 Watt, Cranberg및 Maxwellian 공식들로부터 속 중성자 선량을 계산하여 서로 비교하였다. Watt 및 Cranberg 공식들로 부터 얻어진 속 중성자선량은 Maxwellian 공식으로부터 얻어진 그것보다 약간 높은 값을 보여 주었으며 Watt 공식에 의한 선량계산치는 Cranberg 공식에 의한 그것과 비슷한 값을 보여주었다.

• 한국임상약학회지
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• 제8권1호
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• pp.19-22
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• 1998

Cefixime is an orally absorbed 3rd generation cephalosporin with a broad spectrum of activity against Gram-positive and Gram-negative bacteria and is highly resistant to $\beta-lactamase$ degradation. This study was carried out to evaluate the bioavailability of a new test drug of cefixime (100 mg/capsule) relative to the reference drug. The bioavailability was conducted on 20 healthy volunteers who received a single dose (400 mg) of the test and the reference drugs in the fasting state, in a randomized balanced 2-way crossover design. After dosing, serial blood samples were collected for a period of 12 hours. Plasma was analyzed for cefixime by a sensitive and validated HPLC assay. The major pharmacokinetic parameters $(AUC_{0-12hr},\;C_{max},\;T_{max})$ were calculated from the plasma concentration-time data of each volunteer. The $AUC_{0-12hr},\;C_{max}\;and\;T_{max}$ of the test drug were $36.91\pm11.85\;{\mu}g{\cdot}hr/ml,\;5.47\pm1.61\;{\mu}g/ml,\;and\;4.00\pm0.65\;hr,$ respectively, and those of the reference drug were $34.08\pm8.81\;{\mu}g{\cdot}hr/ml,\;5.25\pm1.40\;{\mu}g/ml,\;and\;4.20\pm0.62\;hr$, respectively. Mean differences of those parameters were 8.32, 4.29, and $4.76\%$, respectively, and the least significant differences at $\alpha$=0.05 for $AUC_{0-12hr},\;C_{max},\;T_{max}$ were 16.02, 13.78, and $11.76\%$, respectively. In conclusion, the test drug was bioequivalent with the reference drug.