• Journal of the Korean Society of Radiology
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• v.10 no.4
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• pp.255-261
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• 2016

In this study, among various factors having influence on SUV, we intended to compare and analyze the change of SUV using CT(4 type) and MRI(3 type) contrast agents which are commercialized now. We used Discovery 690 PET/CT(GE) and NEMA NU2 - 1994 PET phantom as experimental equipment. We have conducted a study as follows; first, we filled distilled water to phantom about two-thirds and injected radioisotope(18F-FDG 37 MBq), contrast agent. Second, we mixed CT contrast agent with distilled water and MRI contrast agent with that water separately. And then, we stirred the fluid and filled distilled water fully not to make air bubble. In emission scan, we had 15minutes scanning time after 40 minutes mixing contrast agent with distilled water. In transmission scan, we used CT scanning and its measurement conditions were tube voltage 120 kVp, tube current 40 mA, rotation time 0.5 sec, slice thickness 3.27 mm, DFOV 30 cm. Analyzing results, we set up some ROIs in 10th, 15th, 20th, 25th, 30th slice and measured SUVmean, SUVmax. Consequently, all images mixed 3 types of MRI contrast agent with distilled water have high SUVmean as compared with pure FDG image but there was no statistical significance. In SUVmax, they have high score and there was statistical significance. And other 4 images mixed 4 types of CT contrast agent with distilled water have significance in both SUVmean and SUVmax. Attenuation correction in PET/CT has been executed through various methods to make high quality image. But we figured out that using CT and MRI contrast agents before PET/CT scanning could make distortion of image and decrease diagnostic value. In that reason, we have to sort out the priority of examination in hospital not to disturb other examination's results. Through this process, we will be able to give superior medical service to our customers.

• Journal of the Korean Society of Radiology
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• v.6 no.6
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• pp.455-464
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• 2012

This study suggested evaluation of approximately exposure to low-dose ionization radiation from medical images using a computed radiography (CR) system in standard X-ray examination and experimental model can compare diagnostic reference level (DRL) will suggest on optimization condition of guard about medical radiation of low dose space. Entrance surface dose (ESD) cross-measuring by standard dosimeter and optically stimulated luminescence dosimeters (OSLDs) in experiment condition about tube voltage and current of X-ray generator. Also, Hounsfield unit (HU) scale measured about each experiment condition in CR system and after character relationship table and graph tabulate about ESD and HU scale, approximately radiation dose about head, neck, thoracic, abdomen, and pelvis draw a measurement. In result measuring head, neck, thoracic, abdomen, and pelvis, average of ESD is 2.10, 2.01, 1.13, 2.97, and 1.95 mGy, respectively. HU scale is $3,276{\pm}3.72$, $3,217{\pm}2.93$, $2,768{\pm}3.13$, $3,782{\pm}5.19$, and $2,318{\pm}4.64$, respectively, in CR image. At this moment, using characteristic relationship table and graph, ESD measured approximately 2.16, 2.06, 1.19, 3.05, and 2.07 mGy, respectively. Average error of measuring value and ESD measured approximately smaller than 3%, this have credibility cover all the bases radiology area of measurement 5%. In its final analysis, this study suggest new experimental model approximately can assess radiation dose of patient in standard X-ray examination and can apply to CR examination, digital radiography and even film-cassette system.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.57-58
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• 2011

III-V족 화합물 반도체의 일종인 InSb는 77 K에서 0.23 eV의 작은 밴드 갭을 가지며 높은 전하 이동도를 가지고 있기 때문에 대기권에서 전자파 흡수가 일어나지 않는 3~5 ${\mu}m$범위의 장파장 적외선 감지가 가능하여 중적외선 감지 소자로 이용되고 있다. 하지만 InSb는 밴드 갭이 매우 작기 때문에, 소자 제작시 누설전류에 의한 소자 특성의 저하가 문제시 되고 있다. 또한 다른 화합물 반도체에 비해 녹는점이 낮고, 휘발성이 강한 5족 원소인 Sb의 승화로 기판의 화학양론적 조성비(stoichiometry)가 변하기 쉬워, 계면특성 저하의 원인이 된다. 따라서 우수한 특성을 가지는 적외선 소자의 구현을 위해서, 저온에서 계면 특성이 우수한 고품질의 절연막 증착 연구가 필수적이다. 본 연구에서는 InSb 기판 위에 $SiO_2$, $Si_3N_4$의 절연막 형성시 증착온도의 변화에 따른 계면 트랩 밀도를 분석하였다. $SiO_2$, $Si_3N_4$ 절연막은 플라즈마 화학 기상 증착법(PECVD)을 이용하여 n형 InSb 기판 위에 증착하였으며, 증착온도를 $120^{\circ}C$부터 $240^{\circ}C$까지 변화시켰다. Metal oxide semiconductor(MOS) 구조 제작을 통하여, 커패시턴스-전압(C-V)분석을 진행하였으며, 절연막과 InSb 사이의 계면 트랩 밀도를 Terman method를 이용하여 계산하였다[1]. 또한, $SiO_2$와 $Si_3N_4$의 XPS 분석과 TOF-SIMS 분석을 통하여 계면 트랩 밀도의 원인을 밝혀 보았다. $120{\sim}240^{\circ}C$ 온도 범위에서 계면 트랩 밀도는 $Si_3N_4$의 경우 $2.4{\sim}4.9{\times}10^{12}cm^{-2}eV^{-1}$, $SiO_2$의 경우 $7.1{\sim}7.3{\times}10^{11}cm^{-2}eV^{-1}$ 값을 나타냈고, 두 절연막 모두 증착 온도가 증가할수록 계면 트랩 밀도가 증가하는 경향을 보였다. 그러나 모든 샘플에서 $Si_3N_4$의 경우, flat band voltage가 음의 전압으로 이동한 반면, $SiO_2$의 경우, 양의 전압으로 이동하는 것을 확인할 수 있었다. 계면 트랩 밀도 증가의 원인을 확인하기 위해서, oxide를 $120^{\circ}C$, $240^{\circ}C$에서 증착시킨 샘플을 XPS 분석을 통하여 깊이에 따른 성분분석을 하였고, 그 결과, $240^{\circ}C$에서 증착된 샘플에서 계면에서 $In_2O_3$와 $Sb_2O_3$ 피크의 증가를 확인하였다. 이는 계면에서 oxide양이 증가함을 의미하며, 이렇게 생성된 oxide는 계면 트랩으로 작용하므로, 계면 특성을 저하시키는 원인으로 작용함을 알 수 있었다. Nitride 절연막을 증착시킨 샘플은 TOF-SIMS 분석을 통해, 계면에서의 성분 분석을 하였고, 그 결과, $240^{\circ}C$에서 증착된 샘플에서 In-N, Sb-N, Si-N 결합의 감소를 확인하였다. 이렇게 분해된 결합들의 dangling 결합이 늘어 계면 트랩으로 작용하므로, 계면 특성을 저하시키는 원인으로 작용함을 알 수 있었다. 최종적으로, 소자특성을 확인 하기 위하여 계면 트랩 밀도가 가장 낮게 측정된 $200^{\circ}C$ 조건에서 $SiO_2$ 절연막을 증착하여 InSb 적외선 소자를 제작하였다. 전류-전압(I-V) 분석 결과 -0.1 V에서 16 nA의 누설 전류 값을 보였으며, $2.6{\times}10^3{\Omega}cm^2$의 RoA(zero bias resistance area)를 얻을 수 있었다. 절연막 증착조건의 최적화를 통하여, InSb 적외선 소자의 특성이 개선됨을 확인할 수 있었다.

• Korean Journal of Animal Reproduction
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• v.21 no.3
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• pp.293-302
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• 1997

Follicular oocytes of Grade I and II were collected from 2~6 mm ovarian follicles and matured in vitro (IVM) for 24 hrs in TCM-199 su, pp.emented with 35$\mu\textrm{g}$/ml FSH, 10$\mu\textrm{g}$/ml LH, and 1$\mu\textrm{g}$/ml estradiol-17$\beta$ at 39$^{\circ}C$ under 5% CO2 in air. They were fretilized in vitro (IVF) by epididymal spermatozoa capacitated with heparin for 12 hrs. The zygotes were then co-cultured in vitro with bovine oviducted epithelial cells (BOEC) for 7 to 9 days. The optimal time for IVM, the successful enucleation of IVM oocytes by micromanipulation at different oocyte ages after IVM, and the ideal culture system for IVM for effective IVF and in vitro development of IVM-IVF embryos was examined for in vitro production of nuclear recipient oocytes and nuclear donor embryos. To improve the efficiency of nuclear transplantation (NT) of IVF embryo into IVM follicular oocytes, this study evaluated the optimal electric condition and oocytes age for activation of IVM oocytes and in vitro development of NT embryos. In vitro development of NT embryos with preactivation or non-preactivation in enucleation oocytes, cell number of IVN-IVF embryos, and NT embryos wre also examined. The results obtained were as follows; 1. The most suitable enucleation time was at 24 hpm (83.3%) rather than that of 28 hpm(69.6%) and 32 hpm(50.0%). 2. There was no difference among the fusion rates of NT embryos at the voltages of 0.75, 1.0 and 1.5 kV/cm, but the in vitro development rates to morule and blastocyst were significantly (P<0.05) higher at the voltage of 0.75(12.5%) and 1.0kV/cm (12.6%) compared to 1.5kV/cm(0%). 3. No significant difference in activation rates were seen in NT embryos stimulated for 30, 60 and 120 $\mu$sec (71.7, 85.2 and 71.9%, respectively), but the in vitro development rates to morulae and blastocyst were significantly (P<0.05) higher in the oocytes stimulated for 30 $\mu$sec (11.6%) and 60 $\mu$sec(10.7%) than 120 $\mu$sec(0.0%). 4. The fusion rates (71.0 and 87.3%) and the in vitro development rates (9.1 and 12.7%) to morula and blastocyst were seen in the NT embryos stimulated at 28 and 32 hpm under the condition of 1.0 kV/ml, 60 $\mu$sec. However, at 24 hpm the fusion rates were 64.8% and the in vitro development to morula and blastocyst were not seen. 5. The fusion rates between the 8~12, 13~17 and 18~22-cell stage of IVM-IVF embryos were not significantly different. The in vitro development rates of the fused embryos to morula and blastocyst which were received from a blastomere of 8~12, 13~17 and 18~22-cell stages of IVM-IVF embryos were 14.9, 8.3 and 6.5%, respectively. 6. The in vitro development rate of the enucleated recipient oocytes with preactivation (24.2%) to morula and blastocyst was significantly (P<0.05) higher than that of non-preactivation (12.8%). 7. The cell numbers of NT blastocyst and IVM-IVF blastocyst cultured during 7~9 days were 63$\pm$11 and 119$\pm$23, and then their the mean cell cycle number were 5.98 and 6.89, respectively.

• Applied Biological Chemistry
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• v.47 no.4
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• pp.390-395
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• 2004

In order to characterize ion channels present in tomato roots, microsomes were incorporated into an artificial lipid bilayer arranged for electrophysiological analysis. Of the five different ion channels that could be found, a channel of 450 pS conductance was found most frequently. This channel displayed subconductance states of 450, 257 and 105 pS. All subconductance states showed linear current-voltage relationships. At positive holding potentials, high frequency of transient channel openings was observed; however, at negative potentials, the open times were long and open probability high. Po was 0.83 at -40 mV. When an additional 50 mM $K^+\;or\;Na^+$ was added to the cis side of bilayer, the reversal potentials shifted in the negative direction to near -10 mV. Thus, the 450 pS cation channel selects poorly between $K^+\;and\;Na^+$. In the presence of $100\;{\mu}M$ metal ions, the channel activity was severely inhibited by $La^{3+},\;Ba^{2+},\;and\;Zn^{2+}$, and Po was decreased to 0.2 or even less. However, $Al^{3+}\;and\;Cd^{2+}$ decreased the activity by only 20%. Interestingly, each metal ion showed different kinetics of channel inhibition. While $500\;{\mu}M\;La^{3+}$ inhibited the activities of all subconductance state, 1 mM $Zn^{2+}$ inhibited all except the 105 pS state. $Cd^{2+}$ changed the gating of the channel from a long-opening state to brief transient openings even at negative holding potentials. These data represent that the metal ions may have different binding sites on the channel protein and could be useful modulators and probes to investigate structural characteristics as well as the functional roles of the 450 pS channel on the root physiology.

• Journal of Sensor Science and Technology
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• v.7 no.3
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• pp.154-162
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• 1998

A planar Bi-Sb multijunction thermal converter with high thermal sensitivity and small ac-dc transfer error has been fabricated by preparing the bifilar thin film Pt-heater and the hot junctions of thin film Bi-Sb thermopile on the $Si_{3}N_{4}/SiO_{2}/Si_{3}N_{4}$-diaphragm, which functions as a thermal isolation layer, and the cold junctions on the dielectric membrane supported with the Si-substrate, which acts as a heat sink, and its ac-dc transfer characteristics were investigated with the fast reversed dc method. The respective thermal sensitivities of the converter with single bifilar heater were about 10.1 mV/mW and 14.8 mV/mW in the air and vacuum, and those of the converter with dual bifilar heater were about 5.1 mV/mW and 7.6 mV/mW, and about 5.3 mV/mW and 7.8 mV/mW in the air and vacuum for the inputs of inside and outside heaters, indicating that the thermal sensitivities in the vacuum, where there is rarely thermal loss caused by gas, are higher than those in the air. The ac-dc voltage and current transfer difference ranges of the converter with single bifilar heater were about ${\pm}1.80\;ppm$ and ${\pm}0.58\;ppm$, and those of the converter with dual bifilar heater were about ${\pm}0.63\;ppm$ and ${\pm}0.25\;ppm$, and about ${\pm}0.53\;ppm$ and ${\pm}0.27\;ppm$, respectively, for the inputs of inside and outside heaters, in the frequency range below 10 kHz and in the air.

• Korean Journal of Food Science and Technology
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• v.35 no.5
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• pp.818-824
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• 2003

Capillary electrophoresis (CE) and near-infrared spectroscopy (NIRS) were performed to discriminate astragalus roots (Astragalus membranaceus) according to geographical origin (domestic or foreign). Two-hundred-and-four astragalus roots were extracted with 30% methanol in 0.1 M phosphate buffer (pH 2.5) and separated in a uncoated fused-silica $(50\;{\mu}m{\times}27\;cm)$ capillary. Conditions for optimal analysis included: temperature $-45^{\circ}C$, voltage -14 kV, and pressure injection time -8 sec. The optimal separation buffer was 0.1 M phosphate buffer (pH 2.5) containing 40 mM hexane sulfonic acid with 20% 2-methoxy ethanol. Raw NIR spectra were obtained using NIRS, and modified partial least square regression was used to develop the prediction model. The correlation coefficient and standard error of prediction were 0.915 and 14.3%, respectively. Under the optimal conditions established for CE and NIRS, the geographical origins of the astragalus roots were correctly identified in 80 and 97%, respectively. Astragalus roots that were not discriminated by NIRS were correctly discriminated by CE. Hence, CE and NIRS are potential methods for discriminating the geographical origins of astragalus roots that complement one another.

• Journal of Radiation Protection and Research
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• v.35 no.1
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• pp.34-42
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• 2010

With the expanded use of radiation in modern medical practices, the most important issue in regards to efforts to reduce individual exposure dose is quality assurance. Therefore in order to study the present condition of quality assurance, the Gwangju Metropolitan City area was divided into five districts each containing ten hospitals. Four experiments were conducted: a reproducibility experiment for kVp, mA, and examination time (sec) intensity of illumination; half-value layer (HVL) measurement; and beam perpendicularity test matching experiment. The tube voltage reproducibility experiment for all fifty hospitals resulted in a 95.33% passing rate and mA and examination time both resulted in a 77.0% passing rate. The passing rate for intensity of illumination was 86.0% and 52.0% for HVL, which was the lowest passing rate of all four factors. For the beam perpendicularity test matching experiment, generally the central flux is matched to within $1.5^{\circ}$. Of all fifty hospitals 30.0% were beyond $3^{\circ}$. The results of the survey showed that 58% responded that they knew about quality assurance cycle. All fifty respondents stated that they have not received any training in regards to quality assurance at their current place of employment. Although quality assurance is making relative progress, the most urgent issue is awareness of the importance of quality assurance. Therefore, the implementation of professional training focusing on safety management and accurate quality assurance of radiation will reduce the exposure to radiation for radiologists and patients and higher quality imaging using less dosage will also be possible.

• Korean Chemical Engineering Research
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• v.55 no.1
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• pp.93-98
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• 2017

This experiment investigated characteristic changes in a $Cu_2ZnSnS_4$(CZTS) solar cell by applying a $Zn(O_x,S_{1-x})$ butter layer with various compositions on the upper side of the absorber layer. Among the four single layers such as $Zn(O_{0.76},S_{0.24})$, $Zn(O_{0.56},S_{0.44})$, $Zn(O_{0.33},S_{0.67})$, and $Zn(O_{0.17},S_{0.83})$, the $Zn(O_{0.76},S_{0.24})$ buffer layer was applied to the device due to its bandgap structure for suppressing electron-hole recombination. In the application of the $Zn(O_{0.76},S_{0.24})$ buffer layer to the device, the buffer layer in the device showed the composition of $Zn(O_{0.7},S_{0.3})$ because S diffused into the buffer layer from the absorber layer. The $Zn(O_{0.7},S_{0.3})$ buffer layer, having a lower energy level ($E_V$) than a CdS buffer layer, improved the $J_{SC}$ and $V_{OC}$ characteristics of the CZTS solar cell because the $Zn(O_{0.7},S_{0.3})$ buffer layer effectively suppressed electron-hole recombination. A substitution of the CdS buffer layer by the $Zn(O_{0.7},S_{0.3})$ buffer layer improved the efficiency of the CZTS solar cell from 2.75% to 4.86%.

• The Journal of Korean Medicine
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• v.19 no.2
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• pp.450-467
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• 1998

To research the characteristics of ion currents induced by inhibitory and excitatory herbs of oriental medicine, we used nystatin-perforated patch clamp technique under voltage clamp condition in periaqueductal gray neuron dissociated from Sprauge-Dawley rat, 10-15 days old. The results are as follows. 1. Ion current induced by $10mg/m{\ell}$ of Bupleuri Radix was inhibited $59.50{\pm}4.29%$ by $10^{-4}M$ bicuculline(p>0.01) but inhibition of $10.75{\pm}4.77%$ by $10^{-4}M$ tubocurarine and $4.75{\pm}4.23%$ by $10^{-4}M$ verapamil had no statistical significance(p>0.05). So ion current induced by Bupleuri Radix revealed only GABA induced $Cl^-$ current, not acetylcholine and $Ca^{2+}$ current. 2. Ion current induced by $20mg/m{\ell}$ of Coptidis Rhizoma was inhibited $47.20{\pm}7.88%$ by $10^{-4}M$ bicuculline(p<0.01) but $3.20{\pm}2.33%$ inhibition by $10^{-4}M$ tubocurarine and $1.00{\pm}1.00%$ inhibition by $10^{-4}M$ verapamil had no significance(p>0.05). So ion current induced by Coptidis Rhizoma revealed only GABA induced $Cl^-$ current, not acetylcholine and $Ca^{2+}$ current. 3. Ion current induced by $20mg/m{\ell}$ of Ecliptae Herba was inhibited $55.00{\pm}4.92%$ by $10^{-4}M$ bicuculline (p<0.01), and also inhibited $15.00{\pm}4.26%$ by $10^{-4}M$ tubocurarine(p<0.05), but inhibition of $6.00{\pm}3.03%$ by $10^{-4}M$ verapamil had no significance(p>0.05). So ion current induced by Ecliptae Herba showed GABA activated $Cl^-$ current and acetylcholine activated cation current, not $Ca^{2+}$ current 4. Ion current induced by $5mg/m{\ell}$ of Liriopis Tuber was inhibited $15.20{\pm}4.57%$ by $10^{-4}M$ bicuculline<0.05) and also inhibited $14.00{\pm}3.00%$ by $10^{-4}M$ tubocurarine(p<0.05), but inhibition of $5.20{\pm}4.80%$ by $10^{-4}M$ verapamil had no significance(p>0.05). So ion current induced by Liriopis Tuber showed GABA. activated $Cl^-$ current and acetylcholine activated cation current, not $Ca^{2+}$ current. 5. Ion current induced by $5mg/m{\ell}$ of Aconiti Tuber was inhibited $97.00{\pm}1.34%$ by $10^{-4}M$ bicuculline(p<0.01), $80.00{\pm}9.83%$ by $10^{-4}M$ tubocurarine(p<0.01), and $24.00{\pm}6.18%$ by $10^{-4}M$ verapamil(p<0.05). So ion current induced by Aconiti Tuber revealed GABA activated $Cl^-$ current and acetylcholine activated cation current and $Ca^{2+}$ current. 6. Ion current induced by $10mg/m{\ell}$ of Zingiberis Rhizoma was inhibited $33.00{\pm}7.43%$ by $10^{-4}$ bicuculline(p<0.05), $10.20{\pm}1.83%$ by $10-^{-4}M$ tubocurarine(p<0.01), and $14.00{\pm}2.16%$ by $10^{-4}M$ verapamil(p<0.01) So ion current induced by Zingiberis Rhizoma revealed GABA activated $Cl^-$ current and acetylcholine activated cation outtent and $Ca^{2+}$ current. 7. Ion current induced by $10mg/m{\ell}$ of Boshniakiae Herba was inhibited $65.00{\pm}13.75%$ by $10^{-4}M$ bicuculline(p<0.05), $38.00{\pm}9.24%$ by $10^{-4}M$ tubocurarine(p<0.05), and $33.25{\pm}7.42%$ by $10^{-4}M$ verapamiHp<0.05). So ion current induced by Bpshniakiae Herba revealed GABA activated $Cl^-$ current and acetylcholine activated cation current and $Ca^{2+}$ current. These results suggest that a point of difference between inhibitory and excitatory herbs is existence of$Ca^{2+}$ current.