• 한국가스학회지
• /
• 제25권1호
• /
• pp.30-39
• /
• 2021

세계적으로 천연가스는 환경적, 정치적, 지역적인 이유로 중요한 에너지원으로 부상하고 있다. 우리나라에서 천연가스는 액화천연가스로 수입하고 있으며, 석탄과 원전을 대체하는 연료나 원료의 활용에서 액화천연가스는 증가하고 있다. 우리나라는 천연가스를 수입에 의존하고 있기 때문에 공급에 대한 안정성분석이 중요하다. 따라서, 본 연구에서는 우리나라 수입구조의 위험도 분석을 통하여 공급리스크를 줄이고 안정적인 공급과 수요를 위한 방안을 제시하였다. 공급위험도를 감소시키기 위해 한 국가로부터의 수입 집중도를 낮춰야 하며, 가스공급안정성 지수 (gas supply security index, GSSI)가 낮은 국가의 수입비중을 낮추고 상대적으로 안정적인 국가인 러시아로부터 수입을 증가시켜야 한다. 또한, 수입국가의 수를 늘리거나 안정적 공급이 가능한 국가와의 관계 유지는 우리나라 수입가스의 공급안정성지표 (total gas supply security index, TGSSI)에 긍정적인 영향을 줄 것으로 분석되었다.

• Journal of Radiation Protection and Research
• /
• 제46권4호
• /
• pp.170-177
• /
• 2021

Background: The International Commission on Radiological Protection is preparing to provide reference dose coefficients for environmental radioiodine intake based on newly developed age-specific biokinetic models. However, the biokinetics of iodine has been reported to be strongly dependent on the dietary intake of stable iodine; for example, the thyroidal uptake of iodine may be substantially lower in iodine-rich regions than in iodine-deficient regions. Therefore, this study attempted to establish a system of age-specific thyroid dose estimation for South Koreans, whose daily iodine intakes are significantly higher than that of the world population. Materials and Methods: Korean age-specific biokinetic parameters and thyroid masses were derived based on the previously developed Korean adult model and the Korean anatomical reference data for adults, respectively. This study complied with the principles used in the development of age-specific biokinetic models for world population and used the ratios of baseline values for each age group relative to the value for adults to derive age-specific values. Results and Discussion: Biokinetic model predictions based on the Korean age-specific parameters showed significant differences in iodine behaviors in the body compared to those predicted using the model for the world population. In particular, the Korean age-specific thyroid dose coefficients for ¹²⁹I and ¹³¹I were considerably lower than those calculated for the world population (25%-76% of the values for the world population). Conclusion: These differences stress the need for Korean-specific internal dose assessments for infants and children, which can be achieved by using the data calculated in this study.

• Journal of Radiation Protection and Research
• /
• 제47권1호
• /
• pp.50-57
• /
• 2022

Background: There are several proton therapy facilities in operation or planned in Taiwan, and these facilities are anticipated to not only treat cancer but also provide beam services to the industry or academia. The simplified approach based on the Monte Carlo-based data sets (source terms and attenuation lengths) with the point-source line-of-sight approximation is friendly in the design stage of the proton therapy facilities because it is intuitive and easy to use. The purpose of this study is to expand the Monte Carlo-based data sets to allow the simplified approach to cover the application of proton beams more widely. Materials and Methods: In this work, the MCNP6 Monte Carlo code was used in three simulations to achieve the purpose, including the neutron yield calculation, Monte Carlo-based data sets generation, and dose assessment in simple cases to demonstrate the effectiveness of the generated data sets. Results and Discussion: The consistent comparison of the simplified approach and Monte Carlo simulation results show the effectiveness and advantage of applying the data set to a quick shielding design and conservative dose assessment for proton therapy facilities. Conclusion: This study has expanded the existing Monte Carlo-based data set to allow the simplified approach method to be used for dose assessment or shielding design for beam services in proton therapy facilities. It should be noted that the default model of the MCNP6 is no longer the Bertini model but the CEM (cascade-exciton model), therefore, the results of the simplified approach will be more conservative when it was used to do the double confirmation of the final shielding design.

• International Journal of Internet, Broadcasting and Communication
• /
• 제13권2호
• /
• pp.145-155
• /
• 2021

With the recent rapid improvement in the standards of life and westernization of dietary lifestyles, the consumption of high-calorie diets such as high-fat and high-protein red meat and instant foods has increased, while less vegetables containing dietary fiber are consumed. In addition to that, stress, erroneous dietary behaviors, and contaminated environments are linked to the risk of developing ulcerative colitis, which is on the rise. Another cause of ulcerative colitis is that involve laxative abuse, including repeated, frequent use of laxatives, and include such conditions as deteriorated bowel function, irritable bowel syndrome, diarrhea, intestinal inflammation, etc. The present study aimed to investigate the comparative evaluation of pharmacological efficacy between sulfasalazine alone and combination with herbal medicine on dextran sodium sulfate (DSS)-induced UC in mice. Balb/c mice received 5% DSS in drinking water for 7 days to induce colitis. Animals were divided into five groups (n = 9): group I-normal group, group II-DSS control group, group III-DSS + sulfasalazine (30 mg/kg), group IV-DSS + sulfasalazine (60 mg/kg), group V-DSS + sulfasalazine (30 mg/kg) + Radish Extract mixture (30 mg /kg) (SRE). DSS-treated mice developed symptoms similar to those of human UC, such as severe bloody diarrhea and weight loss. SRE supplementation, as well as sulfasalazine, suppressed colonic length and mucosal inflammatory infiltration. In addition, SRE treatment significantly reduced the expression of pro-inflammatory signaling molecules through suppression both mitogen-activated protein kinases (MAPK) and nuclear factor-kappa B (NF-κB) signaling pathways, and prevented the apoptosis of colon. Moreover, SRE administration significantly led to the up-regulation of antioxidant enzyme including SOD and Catalase. This is the first report that Radish extract mixture combined with sulfasalazine protects against experimental UC via the inhibition of both inflammation and apoptosis, very similar to the standard-of-care sulfasalazine.

• 대한본초학회지
• /
• 제30권2호
• /
• pp.25-30
• /
• 2015

Objectives : Laver (Porphyra tenera), a red algae species, is one of the most widely consumed edible seaweed in Korea. Laver contains various substances such as essential amino acid, fiber, minerals and polyphenols that benefit human health. In the present study, we prepared ethanol extracts from commercially processed product of Porphyra tenera, and evaluated the growth inhibitory effect against human oral squamous carcinoma YD-10B cells. Methods : Cell viability was measured by MTT assay. Apoptosis was confirmed by TUNEL assay and flow cytometry with the green fluorescent dye FITC annexin V entering apoptotic cells and the red fluorescent dye PI not entering. The expression of the relevant proteins was detected using Western blot. Results : Ethanol extracts of Porphyra tenera (PTE, $50-200{\mu}g/m{\ell}$) caused a significant decrease of cell viability in a dose dependant manner. The cell death occurred as a result of apoptotic process as determined by TUNEL assay and flow cytometric analysis. In line with this observation, decrease in procaspase proteins and increase in cytosolic cytochrome c were observed in cells treated with PTE. In addition, exposure to PTE decreased the expression levels of Bcl-2, and induced PARP cleavage and AIF translocation from mitochondria to nucleus. Conclusions : In conclusion, PTE exerts anti-cancer effects by inducing apoptosis via caspase activation and AIF nuclear translocation in YD-10B cells. These results provide evidence for the possible therapeutic effect of Porphyra tenera in oral cancer cells.

• Wind and Structures
• /
• 제34권5호
• /
• pp.395-405
• /
• 2022

Tornado-induced damages to high-rise buildings and low-rise buildings are quite different in nature. Tornado losses to high-rise buildings are generally associated with building envelope failures while tornado-induced damages to low-rise buildings are usually associated with structural or large component failures such as complete collapses, or roofs being torn off. While studies of tornado-induced structural damages tend to focus mainly on low-rise residential buildings, transmission towers, or nuclear power plants, the current rapid expansion of city centers and development of large-scale building complexes increases the risk of tornadoes impacting tall buildings. It is, therefore, important to determine how tornado-induced load affects tall buildings compared with those based on synoptic boundary layer winds. The present study applies an experimentally simulated tornado wind field to the Commonwealth Advisory Aeronautical Research Council (CAARC) building and estimates and compares its pressure coefficient effects against the Atmospheric Boundary Layer (ABL) flow field. Simulations are performed at the Wind Engineering, Energy and Environment (WindEEE) Dome which is capable of generating both ABL and tornadic winds. A model of the CAARC building at a scale of 1:200 for both ABL and tornado flows was built and equipped with pressure taps. Mean and peak surface pressures for TLV flow are reported and compared with the ABL induced wind for different time-averaging. By following a compatible definition of the pressure coefficients for TLV and ABL fields, the resulting TLV pressure field presents a similar trend to the ABL case. Also, the results show that, for the high-rise building model, the mean and 3-sec peak pressures are larger for the ABL case compared to the TLV case. These results provide a way forward for the code implementation of tornado-induced pressures on high-rise buildings.

• Corrosion Science and Technology
• /
• 제22권1호
• /
• pp.44-54
• /
• 2023

The rupture disk corrosion test (RDCT) method was recently developed to evaluate stress corrosion cracking (SCC) and was found to have great potential for the real-time detection of SCC initiation in a high temperature and pressure environment, simulating the primary water coolant of pressurized water reactors. However, it is difficult to directly measure the stress applied to a disk specimen, which is an essential factor in SCC initiation. In this work, finite element analysis (FEA) was performed using ABAQUS^TM to calculate the stress and deformation of a disk specimen. To determine the best mesh design for a thin disk specimen, hexahedron, hex-dominated, and tetrahedron models were used in FEA. All models revealed similar dome-shaped deformation behavior of the disk specimen. However, there was a considerable difference in stress distribution in the disk specimens. In the hex-dominated model, the applied stress was calculated to be the maximum at the dome center, whereas the stress was calculated to be the maximum at the dome edge in the hexahedron and tetrahedron models. From a comparison of the FEA results with deformation behavior and SCC location on the disk specimen after RDCT, the most proper FE model was found to be the tetrahedron model.

• 한국해안·해양공학회논문집
• /
• 제34권6호
• /
• pp.211-221
• /
• 2022

파의 처오름높이는 제방, 호안 및 방파제와 같은 해안 구조물의 설계에 영향을 미치는 가장 중요한 매개변수 중 하나이다. 본 연구에서는 비정수압 수치모형인 SWASH(Zijlema et al., 2011)를 이용해 고정된 수중 및 부유식 사각형 구조물에 의한 고립파의 처오름높이 저감 효과를 분석하였다. SWASH 수치모형이 고립파의 전파, 쇄파 및 처오름현상을 매우 잘 재현하는 것을 확인하였다. 또한 수중 및 부유식 사각형 구조물에 의한 고립파의 파랑변형을 잘 재현하는 것을 확인하였다. 마지막으로 수중 및 부유식 사각형 구조물의 처오름높이 저감 효과를 검토하였다. 부유식 구조물의 에너지 감쇠효과는 수중 구조물보다 크고, 처오름높이 저감에 더 효과적인 것으로 나타났다.

• Tribology and Lubricants
• /
• 제39권4호
• /
• pp.139-147
• /
• 2023

Cavitation phenomena observed during the operation of a submerged plain journal bearing (PJB) can affect bearing performance parameters such as dynamic coefficients, whirl frequency ratio, and critical mass. This study presents numerical solutions of the Reynolds equation for steadily and dynamically loaded submerged PJBs with half-Sommerfeld (HS), Reynolds, and Jakobsson-Floberg-Olsson (JFO) cavitation models when the supply pressure is larger or equal to the cavitation pressure. The loads at various eccentricity ratios are identical; however, the attitude angle is approximately 6% smaller when the eccentricity ratio is between 0.2 and 0.7 and the JFO model is used, compared to that when the Reynolds model is used. Dynamic coefficients obtained with the HS and Reynolds model show good agreement with each other, except for k_xz, which is sensitive to changes in the force normal to the rotor weight, and is attributed to the difference in the attitude angle obtained with each cavitation model. Stiffness coefficients are determined using the pressure distribution in the film, and therefore, when the JFO model is used, the direct stiffness coefficients are affected and show opposite signs for most eccentricity ratios. The mass-conservative JFO model can predict at least a 30% smaller critical mass compared to that using the HS and Reynolds models. Thus, the instability analysis results can change based on the cavitation model used in a submerged PJB. The results of this research indicate that the JFO model should be used when designing a rotor system supported by submerged PJBs.

• 대한토목학회논문집
• /
• 제30권2A호
• /
• pp.161-168
• /
• 2010

국내 가동 중 일부 원전의 원자로건물에 부착식 텐던이 설치되어 있고, 부착식 텐던에 대한 유효 긴장력 평가는 이들 원전의 계속운전을 위한 주요 현안으로 부각되고 있다. 따라서, 본 연구에서는 System Identification 기법을 이용한 부착식 텐던의 유효 긴장력 평가를 위하여, SI 기법에 유효한 주요 매개변수의 영향 평가를 수행하고 최적의 매개변수를 도출하였다. 본 연구를 위하여, 원자로건물 벽체의 1/5 축소모형 시험체를 제작하였고, 유효 긴장력과 고유진동수 및 변위와의 상관성을 분석하기 위하여 Impact test, SIMO sine sweep test 및 광섬유센서와 변위계에 의한 휨시험을 수행하였다. 시험결과, 고유진동수와 변위 모두 유효 긴장력과 좋은 상관성을 지니는 것으로 나타나, 이들 매개변수 모두 SI 기법의 입력자료로 활용되어 부착식 텐던의 유효 긴장력 예측이 가능한 것으로 분석되었다.