• Progress in Medical Physics
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• v.27 no.1
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• pp.31-36
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• 2016

The paper discusses radiation dose of dual energy CT on which copper modulation layer, is mounted in order to improve diagnostic performance of the dual energy CT. The radiation dose is estimated using MCNPX and its results are compared with that of the conventional dual energy CT system. CT X-ray spectra of 80 and 120 kVp, which are usually used for thorax, abdominal, head, and neck CT scans, were generated by the SPEC78 code and were used for the source specification 'SDEF' card for MCNPX dose modeling. The copper modulation layer was located 20 cm away from a source covering half of the X-ray window. The radiation dose was measured as changing its thickness from 0.5 to 2.0 mm at intervals of 0.5 mm. Since the MCNPX tally provides only normalized values to a single particle, the dose conversion coefficients of F6 tally for the modulation layer-based dual energy CBCT should be calculated for matching the modeling results into the actual dose. The dose conversion coefficient is $7.2*10^4cGy/output$ that is obtained from dose calibration curve between F6 tally and experimental results in which GAFCHORMIC EBT3 films were exposed by an already known source. Consequently, the dose of the modulation layer-based dual energy cone beam CT is 33~40% less than that of the single energy CT system. On the basis of the results, it is considered that scattered dose produced by the copper modulation layer is very small. It shows that the modulation layer-based dual energy CBCT system can effectively reduce radiation dose, which is the major disadvantage of established dual energy CT.

• Journal of the Korean Society of Radiology
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• v.7 no.2
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• pp.121-129
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• 2013

In this study measured patient exposure dose for purpose exposure area and peripheral critical organs by using optically stimulated luminescence dosimeters (OSLDs) from computed tomography (CT), based on the measurement results, we predicted the radiobiological effects, and would like to advised ways of reduction strategies. In order to experiment, OSLDs received calibration factor were attached at left and right lens, thyroid, field center, and sexual gland in human body standard phantom that is recommended in ICRP, and we simulated exposure dose of patients in same condition that equal exposure condition according to examination area. Average calibration factor of OSLDs were $1.0058{\pm}0.0074$. In case of left and right lens, equivalent dose was measure in 50.49 mGy in skull examination, 0.24 mGy in chest, under standard value in abdomen, lumbar spine and pelvis. In case of thyroid, equivalent dose was measured in 10.89 mGy in skull examination, 7.75 mGy in chest, 0.06 mGy in abdomen, under standard value in lumber spine and pelvis. In case of sexual gland, equivalent dose was measured in 21.98 mGy, 2.37 mGy in lumber spine, 6.29 mGy in abdomen, under standard value in skull examination. Reduction strategies about diagnosis reference level (DRL) in CT examination needed fair interpretation and institutional support recommending international organization. So, we met validity for minimize exposure of patients, systematize influence about exposure dose of patients and minimize unnecessary exposure of tissue.

• The korean journal of orthodontics
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• v.28 no.2 s.67
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• pp.311-327
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• 1998

The purpose of this study was to evaluate the effects of Transforming Growth Factor-${\beta}$ (TGF-${\beta}$) on the viability of human periodontal ligament cells, in-vitro and on the experimental tooth movement in rat, in-vivo. Human periodontal ligaments were cultured from the first premolar tooth extracted for the purpose of the orthodontic treatment. 0.1, 1, 5 and 10ng/m1 of TGF-${\beta}$ was given to the cultured wells, respectively and the viability was evaluated by MTT assay. Twenty Sprague-Dawley rats were divided into 5 experimental groups(4 rats in each) where 100g of force was applied from helical spring across the maxillary incisors. TGF-${\beta}$ was injected via Hamilton syringe into the periodontal ligament at the mesial and the distal surface of a maxillary incisor of 2 rats in each experimental group. Phosphate buffer saline(PBS) was injected in 2 other rats as controls. Experimental groups were sacrificed at 1, 3, 7, 14 and 28 days after force application, respectively. The obtained tissues were evaluated histologically. The obtained results were as follows: 1. The viability of periodontal ligament cells in 0.1ng/ml of TGF-${\beta}$ was not significantly different from that of control at 1-, 2- and 3-day of cultivation. 2. The viability of periodontal ligament cells was significantly increased at 3-day in 1ng/ml or 5ng/ml of TGF-${\beta}$, and at 2-,3-day in 10ng/ml of of TGF-${\beta}$. 3. The zone of hyalinization in periodontal ligament in pressure side was smaller in TGF-${\beta}$ injection group than that in control group at 3-day after the application of experimental force in rat. But no difference was seen after 7-day. 4. Osteoclastic activity and capillary prolieferation in pressure side were greater in TGF-${\beta}$ injection group than that in control group at 3-day to 7-day. 5. Osteoblastic activity and new bone fomation in tension side were greater in TGF-${\beta}$ injection group than that in control group at 3-day to 14-day.

• The Journal of Korean Society for Radiation Therapy
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• v.29 no.1
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• pp.77-84
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• 2017

Purpose: To evaluate the image quality improvement and dosimetric effects on virtual monochromatic images of a Dual Source-Dual Energy CT(DS-DECT) for radiotherapy planning. Materials and Methods: Dual energy(80/Sn 140 kVp) and single energy(120 kVp) scans were obtained with dual source CT scanner. Virtual monochromatic images were reconstructed at 40-140 keV for the catphan phantom study. The solid water-equivalent phantom for dosimetry performs an analytical calculation, which is implemented in TPS, of a 10 MV, $10{\times}10cm^2$ photon beam incident into the solid phantom with the existence of stainless steel. The dose profiles along the central axis at depths were discussed. The dosimetric consequences in computed treatment plans were evaluated based on polychromatic images at 120 kVp. Results: The magnitude of differences was large at lower monochromatic energy levels. The measurements at over 70 keV shows stable HU for polystyrene, acrylic. For CT to ED conversion curve, the shape of the curve at 120 kVp was close to that at 80 keV. 105 keV virtual monochromatic images were more successful than other energies at reducing streak artifacts, which some residual artifacts remained in the corrected image. The dose-calculation variations in radiotherapy treatment planning do not exceed ${\pm}0.7%$. Conclusion: Radiation doses with dual energy CT imaging can be lower than those with single energy CT imaging. The virtual monochromatic images were useful for the revision of CT number, which can be improved for target coverage and electron densities distribution.

• The Korean Journal of Nuclear Medicine
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• v.4 no.1
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• pp.27-36
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• 1970

적혈구(赤血球) 수명의 측정에는 $^{51}Cr$-표지적혈구법(標識赤血球法)이 임상적(臨床的)으로 이용(利用)되고 있으며 이는 이론상(理論上) steady state 즉(卽) 측정기간(測定期間)동안 순환(循環) $^{51}Cr$량(量)-적혈구량(赤血球量)이 일정(一定)할 때에 한(限)하여 유효(有效)하며 unsteady state 때는 true red cell survival을 알기 위하여서는 측정치에 영향을 주는 요인(要因)에 대하여 각각(各各) 교정(校正)해 줄 필요(必要)가 있다. 이 요인(要因)중에 특히 실혈(失血)로 인(因)한 영향에 관(關)하여는 계통적인 연구(硏究)가 적다. 이에 저자(著者)들은 $^{51}Cr$표지적혈구법(標識赤血球法)을 이용(利用)하여 실혈(失血)이 적혈구(赤血球) 수명측정(測定)에 미치는 영향을 인체(人體)에서 실험 관찰하여 몇가지 성적을 얻었다. 연구대상(硏究對象)은 총(總) 56명(名)의 청장년(靑壯年)으로 급성실혈군(急性失血群)과 만성실혈군(慢性失血群)으로 구분(區分)하여 급성실혈군(急性失血群)은 위장출혈등(胃腸出血等)이 없는 2대(代)의 의대생(醫大生)으로 $^{51}Cr$표지적혈구법(標識赤血球法)을 사용하여 적혈구(赤血球) 수명을 측정하는 동안($10{\sim}14$ 일간(日間)) 1일당(日當) 10ml(6명(名)), 25ml(4명(名)), 50ml(4명(名)), 75ml(4명(名)), 100ml(6명(名))를 각각(各各) 사혈(瀉血)한 군(群)과 10일간(日間) 1,000ml를 사혈한 군(群) 즉 200ml씩 5회(回)(4명(名)), 500ml씩 2회(回)(4명(名))로 세분(細分)하였으며 만성실혈군(慢性失血群)은 직업적인 공혈자(供血者)로 반복사혈로 생긴 9명(名)의 빈혈자와 십이지장충증(十二指腸蟲症)에 감염(感染)되어 구충(驅蟲)한 중등도(中等度)의 철결핍성 빈혈환자 7명(名)으로 나누어 관찰하였다. 측정(測定) 방법(方法)으로는 Gray 및 Sterling법(法)을 개설한 방법(方法)으로 $^{51}Cr$표지적혈구(標識赤血球)의 계측시료(計測試料)로서 전혈(全血) 및 적혈구(赤血球)를 사용(使用)하였다. 실험(實驗)성적은 1. 1일당(日當) 실혈량(失血量)이 증가(增加)할수록 적혈구(赤血球)수명($T\frac{1}{2}$)은 짧아짐을 알 수 있었다. 즉(卽) 1일당(日當) $20{\sim}50ml$ 사혈군에서는 $T\frac{1}{2}$이 현저히 짧아지는 rapid phase을 나타내고 1일당(日當) 50ml이상(以上) 사혈군에서는 짧아지는 정도(程度)가 완만한 slow phase을 나타낸다(Fig. 6). 2. 1일량(日量) 10ml 및 25ml식(式) 사혈한 군(群)의 적혈구수명(赤血球壽命)을 측정(測定)하는데 있어 적혈구(赤血球)를 사용하였을 때에는 $T\frac{1}{2}$측 정치에 유의한 차(差)가 없었으며 이 범위 내에서는 Hct., Hb. 및 혈청철치(血淸鐵値)도 역시 유의한 차(差)가 없었다. 3. 1일량(日量) 50ml 및 75ml, 100ml씩 사혈한 군(群)에서는 적혈구(赤血球)만을 사용(使用)하였을 때와 전혈(全血)을 시료(試料)로 하였을 때 사이에 $T\frac{1}{2}$의 측정치에 유의한 차(差)가 있었으며 이 때는 Hct., Hb. 및 혈청철치(血淸鐵値)에도 변화(變化)가 있었다. 즉(卽), 전혈(全血)을 사용한 적혈구(赤血球) 수명($T\frac{1}{2}$)의 측정치가 적혈구(赤血球)만를 사용(使用)한 적혈구(赤血球) 수명($T\frac{1}{2}$)의 측정치 보다 짧았다. 4. 일정(一定)기간(10 일(日)) 사혈의 총량(1000ml)이 같을 매는 200ml를 5회(回) 사혈한 군(群)이나 500ml를 2회(回) 사혈한 군(群) 사이에 적혈구(赤血球) 수명($T\frac{1}{2}$)에 유의(有義)한 차(差)를 볼 수 없었다. 5. 직업적 공혈자의 반복사혈로 인(因)한 만성(慢性) 빈혈환자 9명(名)에서의 $^{51}Cr$적혈구(赤血球)수명($T\frac{1}{2}$) 측정치는 평균(平均) 19.2일(日)로 짧아져 있으나 적혈구수명측정전후(赤血球壽命測定前後)에 충분(充分)한 철제(鐵劑)를 투여(投與)하여 Hct., Hb. 및 혈청철치(血淸鐵値)를 증가(增加)시켰으며 이때 볼 수 있었든 Hct치(値)를 규준(規準)하여 교정한 적혈구(赤血球)수명($T\frac{1}{2}$)은 거의 정상(正常)범위 안에 있어(27.6일(日)) 이러한 인자(因子)를 고려하지 않으면 잘못 이해할 수가 있다. 6. 구충자충(鉤蟲仔蟲)을 구충한 7명(名)의 중등도(中等度) 철(鐵)결핍성 빈혈환자에서의 적혈구(赤血球)수명($T\frac{1}{2}$) 측정치는 25일(日)$\sim$31일(日)로 평균(平均) 28일(日)이었으며, 이때 장 출혈량은 1일(日) $1.0{\sim}3.5ml$이었다. 단시일내의 급성실혈시에는 이와같은 소량의 실혈(失血)도 적혈구(赤血球)수명($T\frac{1}{2}$) 측정치에 영향을 보여 줌을 알 수 있었다. 따라서 이러한 정도의 실혈은 실험오차에 기인하는 것인지 아니면 장기 출혈에서는 이러한 소량의 실혈이 적혈구(赤血球)수명($T\frac{1}{2}$) 측정에 영향을 미치지 않는 것인지는 아직 확실히 말할 수 없다. 8. $^{51}Cr$-표지적혈구(標識赤血球)로 측정한 적혈구(赤血球)수명($T\frac{1}{2}$)은 측정시의 실혈량(失血量)에 큰 영향을 받음을 알 수 있으며 저자(著者)들은 $^{51}Cr$표지적혈구(標識赤血球)를 이용(利用)한 적혈구(赤血球) 수명 측정때 검사기간중 실혈량이 적혈구수명치(赤血球壽命値)에 미치는 관계를 상술(上述)한 실험치(實驗値)를 기초(基礎)로 하여 다음과 같을 교정식(校正式)을 고찰(考察)해 보았다. $^{51}Cr\;T\frac{1}{2}=17.0e^{-0.0495}+18.4e^{-0.000924x}$ 단(但) X : 1일(日) 실혈량(失血量)(단위(單位) ml)

• Korean Journal of Cognitive Science
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• v.17 no.2
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• pp.75-102
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• 2006

Three experiments were conducted using a verification task to examine good and poor readers' generation of causal inferences(with because sentences) and contrastive inferences(with although sentences). The unfamiliar, critical verification statement was either explicitly mentioned or was implied. In Experiment 1, both good and poor readers responded accurately to the critical statement, suggesting that both groups had the linguistic knowledge necessary to the required inferences. Differences were found, however, in the groups' verification latencies. Poor, but not good, readers responded faster to explicit than to implicit verification statements for both because and although sentences. In Experiment 2, poor readers were induced to generate causal inferences for the because experimental sentences by including fillers that were apparently counterfactual unless a causal inference was made. In Experiment 3, poor readers were induced to generate contrastive inferences for the although sentences by including fillers that could only be resolved by making a contrastive inference. Verification latencies for the critical statements showed that poor readers made causal inferences in Experiment 2 and contrastive inferences in Experiment 3 doting comprehension. These results were discussed in terms of context effect: Specific encoding operations performed on anomaly backgrounded in another passage would form part of the context that guides the ongoing activity in processing potentially relevant subsequent text.

• Journal of the Korean Society of Radiology
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• v.7 no.1
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• pp.17-24
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• 2013

This study estimate radiation biological danger factor by measuring patient's exposed dose and propose the low way of patient's exposed dose in panoramic radiography. We seek correcting constant of OSL dosimeter for minimize the error of exposed dose's measurement and measure the Left, Right crystalline lens, thyroid, directly included upper, lower lips, the maxillary bone and the center of photographing that indirect included in panoramic radiography by using the human body model standard phantom advised in ICRP. In result, the center of photographing's level of radiation maximum value is $413.67{\pm}6.53{\mu}Gy$ and each upper, lower lips is $217.80{\pm}2.98{\mu}Gy$, $215.33{\pm}2.61{\mu}Gy$. Also in panoramic radiography, indirect included Left, Right crystalline lens's level of radiation are $30.73{\pm}2.34{\mu}Gy$, $31.87{\pm}2.50{\mu}Gy$, and thyroid's level of measured exposed dose can cause effect of radiation biological and we need justifiable analysis about radiation defense rule and substantiation advised international organization for the low way of patient's exposed dose in panoramic radiography of dental clinic and we judge need the additional study about radiation defense organization for protect the systematize protocol's finance and around internal organs for minimize until accepted by many people that is technological, economical and social fact by using panoramic measurement.

• Progress in Medical Physics
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• v.11 no.1
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• pp.59-71
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• 2000

It is possible to obtain a fast CT scan during breath holding with spiral technique. But the risk of radiation is increased due to detailed and repeated scans. However, the limitation of X-ray doses is not fully specified on CT, yet. Therefore, the purpose of the present study is to define the limitation of X-ray doses on CT The CT unit was somatom plus 4. Alderson Rando phantom, Solenoid water phantom, TLD, and reader were used. For determining adequate position and size of organs, the measurement of distance(${\pm}$2mm) from the midline of vertebral body was performed in 40 women(20~40 years). On the brain scan for 8:8(8mm slice thickness, 8mm/sec movement velocity of the table) and 10:10(10mm slice thickness, 10mm/sec movement velocity of the table) methods, the absorption doses of exposed area of the 10:10 were slightly higher than those of 8:8. The doses of unexposed uterus were negligible on the brain scan for both 8:8 and 10:10. On the chest scan for 8:8, 8:10(8mm slice thickness, 10mm/sec movement velocity of the table), 10:10, 10:12(10mm slice thickness, 12mm/sec movement velocity of the table) and 10:15(10mm slice thickness, 15mm/sec movement velocity of the table) methods, 8:8 method of the absorption doses of exposure area was the most highest and 10:15 method was the most lowest. The absorption doses of 8:10 method was relatively lower than those of the other methods. In conclusion, the 8:10 method is the most suitable to give a low radiation burden to patient without distorting image quality.

• Korean journal of food and cookery science
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• v.22 no.3 s.93
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• pp.396-401
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• 2006

This study was performed to determine the quality characteristics of Jeung-Pyun with added tapioca flour. With increasing tapioca flour content, the moisture content of the product was decreased. The addition of tapioca flour increased the volume and symmetry compared to the control with no tapioca flour. The highest uniformity was shown by the 10% added group, but the differences were not significant. In the Hunter's value, the lightness of the control was higher than that of the group with added tapioca flour. Whereas the reverse was the case for the yellowness. With increasing tapioca flour content, the springiness, gumminess, cohesiveness, and chewiness of Jeung-Pyun were increased, and the hardness increased. In sensory evaluation cell uniformity and chewiness were the highest in the 20% added group. The hardness of the sense examination increasing with increasing tapioca floor content. The overall quality of Jeung-Pyun was the lowest in the 30% added group.

• Korean journal of food and cookery science
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• v.22 no.3 s.93
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• pp.307-313
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• 2006

Tofu was prepared with various herbs (green tea, rosemary, lavender and thyme) and the tofu quality was investigated during storage. In the measurement of tofu color, the L and b values increased during storage period. Especially, the b value was very high at 8 days after storage. The pH value of tofu increased until 6 days of storage, but then decreased. The turbidity gradually increased until 6 days of storage and rapidly increased at 8 days of storage. The microorganism count of herb tofu was lower an that of control tofu during storage. Especially green tea tofu showed the lowest psychrotrophic microorganism count as $1.3{\times}10^8\;CFU/g$. In addition, lavender tofu showed the lowest aerobic mesophilic microorganism count $(2.0{\times}10^7\;CFU/g)$ at 8 days of storage. In texture analysis, hardness and chewiness of herb tofu increased with increasing storage period. Springiness increased to 2 or 4 days of storage but decreased after 6 or 8 days. Therefore, herb tofu is expected to have good quality physiologically as well as microbiologically.