• 한국의학물리학회지:의학물리
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• 제14권2호
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• pp.81-89
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• 2003

근접조사용 선원으로 직경이 0.5 mm에 길이 3.5 mm인 Ir-192선원을 고안하고, 선량알고리즘을 개발하였다. 선원을 0.1 mm 두께로 균등분할하고 총 875개의 미소선원으로부터 조직에 도달되는 선량을 계산하고 선량분포를 조사하였다. 선원을 감싸는 캡슐용기의 두께는 0.3 mm이며, 선량기준점인 Ir선원의 Air-kerma strength(S$_{k}$ ) 는 mCi당 4.108U를 얻었으며 선원 측방의 1 cm에서 1.154 Uh$^{-1}$ (1.3167${\times}$$10^{-3}$cGy/mCi-sec)의 조직선량률을 얻었다. Air-kerma strength로부터 조직내 선량률상수(Λ)는 Ir-192에너지 스펙트럼과 실험치인 조직내 산란보정계수를 적용하여 1.154 cGy h$^{-1}$U$^{-1}$ 얻었다. 선량분포의 특성은 선원 축방향으로 56%의 상대선량률을 보였고, 케이블측의 선량감쇠는 50%를 보였다. 마이크로선원의 중심에서 반경 1 cm 주위의 선량분포와 5 cm의 선량분포를 비교한 결과 반경이 큰 경우의 측방선량에 비해 축 방향의 선량이 약 2% 감쇠함을 보았다. 선원자체의 필터효과는 점선원에 비해 88.3%의 선량률을 얻어 약 12%의 감쇠를 보였으며, 캘슐벽의 필터효과는 약 3% 정도로 미미하게 나타났으며 기준점에서 선량필터효과는 약 15.6% 감쇠되는 것으로 나타났다. Ir-192 선원과 같이 에너지가 낮은 선원을 사용하는 경우 선량분포특성에 따라 아프리케이터의 직경을 크게 하여 선원 축 방향의 선량저하를 피할 수 있음을 알 수 있었다.

• 대한방사선기술학회지:방사선기술과학
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• 제32권3호
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• pp.299-306
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• 2009

MDCT의 시간분해능 향상과 등방성 해상능(isotrophic resolution) 영상의 획득, 그리고 지능적인 심전도 동조를 바탕으로 하여 심혈관 질환의 효과적인 진단검사로 인정받고 있는 후향적 심전도 동조화(retrospective ECG gating) 하의 coronary CT angiography는 상대적으로 많은 환자선량을 제공함으로 인해 우수한 진단방법으로서의 장점을 반감시키고 있다. 이에 각 장치 제조사에서는 환자선량을 감소시키는 방법의 연구가 활성화되어 왔으며, 이의 일환으로 지능적인 cardiac dose modulation 기술과 전향적 심전도 동조화(prospective ECG gating)를 사용한 sequential scan이 도입되고 있다. 이에 본 연구에서는 64 채널 MDCT에서 54 kg, 163 cm인 여성 인체모형팬텀을 대상으로 하고 형광유리선량계를 사용하여 후향적 심전도 동조화 하의 coronary CT angiography 프로토콜에서 환자선량의 정량적 평가와 환자선량 감소를 위해 본원에서 선택적으로 적용하고 있는 5가지 검사 프로토콜을 적용하였을 경우의 effective dose와 중요 부위의 organ dose를 측정 비교하여 다음과 같은 결과를 얻었다. 1) Dose modulation없이 120 kVp와 210 mAs의 노출조건으로 retrospectively ECG gated helical scan으로 시행한 conventional coronary CT angiography 프로토콜의 effective dose는 17.8 mSv였으며, 심장의 organ dose는 103.8 mGy였다. 2) 관전압을 120 kVp에서 100 kVp로 낮추었을 경우 effective dose는 11.0 mSv로 conventional coronary CT에 비해 38.2%가 감소하였으며, 심장은 67.3 mGy로 45.2%가 감소하였다. 3) Cardiac dose modulation을 적용한 경우 effective dose는 13.3 mSv로 conventional coronary CT에 비해 25.3%가 감소하였으며, 심장은 80.0 mGy로 22.9%가 감소하였다. 4) 100 kVp의 저관전압과 cardiac dose modulation을 적용한 경우 effective dose는 8.1 mSv로 conventional coronary CT angiography에 비해 54.5%가 감소하였으며, 심장은 49.5 mGy로 52.3%가 감소하였다.

• Preventive Nutrition and Food Science
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• 제3권4호
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• pp.339-343
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• 1998

Gamma-irradiated chicken at dose levels of 0.1 to 10 kGy was subjected to detection of radiation-induced hydrocarbons whether irradiated or not. The hydrocarbons extracted from chicken fat were separated by florishil column chromatography and identified with GC-FID and GC/MS methods. Eight kinds of hydrocarbons were identified from irradiated chicken, among which 1, 7-hexadecadiene and 8-heptadencene were detected as major compounds , Remarkably radiation-induced hydrocarbons in irradiated chiken were detected at 0.5kGy and over. The concentration of radiation-induced hydrocarbons was relatively constant during 16 weeks.

• 한국환경보건학회지
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• 제30권1호
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• pp.59-64
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• 2004

This study was carried out to investigate influencing factors of bisphenol A(BPA) removal characteristic in conventional water treatment systems to be connected with coagulation, sedimentation, filtration and disinfection. The result are summarized as follows; In BPA removal, optimal doses of PAC, alum, ferric chloride were 7.5 mg Al/L, 10.0 mg AI/L, 15.0 mg Fek. PAC was most effective coagulant to remove BPA. In coagulation process, BPA removal efficiency were increased about 2％ by adjusting pH of raw water as 6. At temperature rise 1$0^{\circ}C$, BPA removal efficiency were increased 0.94％. but BPA removal efficiency in sand filtration process were under 1 ％ie, so that BPA was almost not removed. At free chlorine dose 1, 2 mg/L, the reaction rate constant k in the BPA removal have been calculated to be 0.397, 0.953 min$^{-1}$ . At free chlorine dose 1, 2 mg/1-, degradation reaction of BPA was completed during 10 min and BFA removal efficiencies were 97.66, 99.99％ at this time.

• 대한가정학회지
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• 제30권3호
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• pp.101-117
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• 1992

Effects of gamma irradiation(2.5∼20kGy) on water absorption property was studied for a local variety of black soybeans. In water absorption patterns of black soybeans, the time to reach a fixed moisture content was reduced depending on the increment of water soaking temperature and irradiation dose. Irradiation at 2.5∼10kGy resulted in the reduction of soaking time of black soybeans by about 1∼3 hours and the increase of hydration capacity by 10∼20%, respectively, compared to the nonirradiated control black soybean. The water uptake rate constant of the irradiated black soybean difinitely increased with the increase of dose levels and water soaking temperature. The activation energy for water absorption and z-value were lower in the irradiated black soybeans than in the nonirradiated control black soybean. The efficacy of water absorption property in the irradiated black soybeans was also recognized after one year of storage at room temperature.

• Biomolecules & Therapeutics
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• 제27권5호
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• pp.435-441
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• 2019

The capsaicin receptor TRPV1 (transient receptor potential vanilloid 1) has been an object of intense interest for pharmacological development on account of its critical role in nociception. In the course of structure activity analysis, it has become apparent that TRPV1 ligands may vary dramatically in the rates at which they interact with TRPV1, presumably reflecting differences in their abilities to penetrate into the cell. Using a fast penetrating agonist together with an excess of a slower penetrating antagonist, we find that we can induce an agonist response of limited duration and, moreover, the duration of the agonist response remains largely independent of the absolute dose of agonist, as long as the ratio of antagonist to agonist is held constant. This general approach for limiting agonist duration under conditions in which absolute agonist dose is variable should have more general applicability.

• 대한방사선기술학회지:방사선기술과학
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• 제19권2호
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• pp.71-77
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• 1996

Studies were conducted to determine the clinical application of photodiode. We compared photodiode with ion-chamber as to change of tube potential, tube current, mAs and measured decreasing rate of penetration dose. When tube potential was changed from 60 kVp to 120 kVp, output of photodiode and ion-chamber were changed from 0.4 to 1.625, and 1.018 to 4.268, respectively. This was a good agreement to theory that $I=Kv^2it$(I is intensity, K is constant, v is tube potential, i is tube current, t is time). Characteristics for change of tube current and mAs were also a good agreement to theory. And comparison in decreasing rate of penetration dose was similar except above 6 cm in depth. Our results indicated that photodiode was a good instrument for relative measurement of radiation exposure, but we can not use the photodiode for absolute radiation dose.

• 한국환경보건학회지
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• 제30권5호
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• pp.358-365
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• 2004

The photocatalytic oxidation of Rhodamine B(RhB) was studied using photocatalytic reactor filled with module of quartz tube. Module of quartz tube consisted of small quartz tube (inner diameter, 1.5 mm; outer diameter, 3 mm) bundle coated with powder $TiO_2$ and uncoated large quartz tube (inner diameter, 20 mm; outer diameter, 22 mm). Two 30 W germicidal lamp was used as the light source and the reactor volume was 0.5 l. The effects of parameters such as the coating materials and numbers, initial concentration, $H_{2}O_2$ dose and metal deposition (Ag, Pt and Fe) and simultaneous application of $H_{2}O_2$ and metal deposition. The results showed that the initial reaction constant of quartz module coated with powder $TiO_2$ was higher 1.4 time than that of the $TiO_2$ sol and optimum coating number is twice. In order to increase reaction rate, simultaneous application of photocatalytic and photo-fenton reaction using Fe coating and dose $H_{2}O_2$ dose increased reaction rate largely.

• Journal of Nutrition and Health
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• 제25권7호
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• pp.597-607
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• 1992

The present study examined effects of caffeine on coronary circulation myocardial oxygen me-tabolism and calcium release in isolated perfused guinea pig hearts. Intracoronary caffeine({{{{ {10 }^{-5 } }}}}∼{{{{ { 10}^{-3 } }}}}M) was employed for 10 minutes to measure coronary perfusate flow(CF) and coronary vascular sresistance(CVR) at a constant coronary perfusion pressure of 80 cmH2O Perfusate myocardial oxygen consumption(MVO2) and percent oxygen extraction(%EC2) were calcula-ted. In addition calcium contents in both perfusate samples were measured to calculate calcium release in coronary venous effluent. Caffeine significantly decreased CF and increased CVR during 10 minutes of caffeine perfusion regardless of dose of caffeine perfused exhibiting time-response. While % EO2 was significantly enhanced with caffeine MVO2 was markedly reduced. The coronary venous perfusate pH dcreased during the perfusion with caffeine. These changes were consistent with caffeine-induced metabolic acidosis. Calcium release appeared to be dose-dependent and high dose of caffeine greatly increased venous calcium release even 2 minutes after perfusion with carffeine. These finding in dicate that caffeine produced coronary vasoconst-riction with increased calcium release in isolated perfused guinea pig hearts. Additionaly this vasoconstrictor response mignt be due tin part to the direct actions of caffeine.

• Macromolecular Research
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• 제11권3호
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• pp.146-151
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• 2003

The dependence of electrical conductivity on concentrations of diallyldimethylammonium chloride (DADMAC) monomer, linear poly(DADMAC) and their mixture monomer/poly(DADMAC) in dilute aqueous solution exhibits a linear relationship. It was possible to calculate conversion of DADMAC polymerization by measuring its electric conductivity. Although the electrical conductivity of the poly(DADMAC) solution decreased with increasing its molecular weight, in the process of UV or ionizing radiation polymerization the molecular weight of the polymers could be kept constant in the case of fixed temperature, UV-luminous intensity or dose rate. Based on the method mentioned above, the kinetics of UV induced polymerization of DADMAC in aqueous solution was studied; the overall activation energy of polymerization of DADMAC in the water phase was calculated to be 18.8 kJ mol$^{-1}$ . ${\gamma}$-Radiation-induced polymerization of DADMAC in aqueous solution as a function of absorbed dose was studied as well. The conversion of DADMAC increased quickly with dose before 30 kGy and then increased slowly. The experimental data of both UV- and ${\gamma}$-induced polymerization were verified to be reliable by inverted ultracentrifugation method.