• Nuclear Engineering and Technology
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• 제54권10호
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• pp.3614-3619
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• 2022

To operate the ion cyclotron resonance heating (ICRH) antennas in a better heating state and produce relatively low impurities, it is necessary to control the antenna spectrum by changing the antenna phasing. As the electrical length of the antenna feeding transmission lines is changing as a matter of the standing wave pattern at the ceramic supports, 90° elbows, T-connectors and antenna loops, we chose to measure the current at the grounding points of the antenna loops by antenna strap probe. The voltage drops along a small, several millimeter-long paths at the end of the antenna loops give a signal that is proportional to the current in the antenna loop. Through the simulation of the antenna strap probe and the actual measurement of the antenna phasing under vacuum conditions, the reliability of the antenna strap probe based diagnostic system have been successfully proved. Moreover, this system was successfully applied to the ICRH daily experiments in the spring of 2021. In the near future, the active real-time feedback control of the antenna phasing system will be developed based on this diagnostic system in the EAST tokamak.

• Nuclear Engineering and Technology
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• 제54권11호
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• pp.4146-4158
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• 2022

Ultra-high performance concrete (UHPC) has been widely utilized in military and civil protective structures to resist intensive loadings attributed to its excellent properties, e.g., high tensile/compressive strength, high dynamic toughness and impact resistance. At present, aiming to improve the defects of the traditional vertical concrete cask (VCC), i.e., the external storage facility of spent fuel, with normal strength concrete (NSC) shield, e.g., heavy weight and difficult to fabricate/transform, the feasibility of UHPC applied in the shield of VCC is numerically examined considering its high radiation and corrosion resistance. Firstly, the finite element (FE) analyses approach and material model parameters of NSC and UHPC are verified based on the 1/3 scaled VCC tip-over test and drop hammer test on UHPC members, respectively. Then, the refined FE model of prototypical VCC is established and utilized to examine its dynamic behaviors and damage distribution in accidental tip-over and end-drop events, in which the various influential factors, e.g., UHPC shield thickness, concrete ground thickness, and sealing methods of steel container are considered. In conclusion, by quantitatively evaluating the safety of VCC in terms of the shield damage and vibrations, it is found that adopting the 300 mm-thick UHPC shield instead of the conventional 650 mm-thick NSC shield can reduce about 1/3 of the total weight of VCC, i.e., about 50 t, and 37% floor space, as well as guarantee the structural integrity of VCC during the accidental drop simultaneously. Besides, based on the parametric analyses, the thickness of concrete ground in the VCC storage site is recommended as less than 500 mm, and the welded connection is recommended for the sealing method of steel containers.

• Nuclear Engineering and Technology
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• 제55권7호
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• pp.2621-2627
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• 2023

In Experimental Advanced Superconducting Tokamak (EAST) experiments, to achieve long pulse and high-power ICRH system operation, a new kind of ICRH antenna has been designed. One of the most critical factors in limiting the operation of long pulse and high power is the intense heat load in the front face of the ICRH antenna, especially the Faraday Screen (FS). Therefore, the cooling channels of FS need to be designed. According to thermal-hydraulic analysis, the FS tubes are divided into several groups to achieve more excellent water cooling capability. The number of series and parallel tubes in one group is chosen as six. This antenna went into service in the spring of 2021, and it is delightful that the temperature distribution of the FS tube is below 400 ℃ in 14.5 s and 1.8 MW ICRH system operation. However, the active water-cooling design was not carried out on the upper and lower plates of FS, which led to severe ablations on that region under long pulse and high power operation, and the temperature is up to 800. Therefore, the upper and lower side plates of the FS were designed with water cooling based on thermal-hydraulic analysis. During the 2022 winter experiments, the temperature of ICRH antenna FS was lower than 400 in the pulse of 200s and the power of 1 MW operation.

• Fisheries and Aquatic Sciences
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• 제26권11호
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• pp.649-659
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• 2023

The present study compared the structure of mixilliped of Fenneropenaeus chinensis between the larval and adult stage and investigated the effect of the structural difference on the immunity of F. chinensis. A fourteen day and a one-month long culture trial were conducted each with postlarvae and adults of F. chinensis in the biofloc, mixed water (50% biofloc:50% clear seawater) and seawater control. Immune-related genes mRNA expressions of postlarvae was analysed by quantitative reverse transcription polymerase chain reaction (qRT-PCR). And the analysis of adult stage immunity was carried out using phenoloxidase (PO) enzyme activation in haemocyte. In the postlarvae, the final body weights were 51.43 and 58.47 mg for the biofloc water and the control seawater, respectively. On the other hand, the final body weights of the adults were significantly different between biofloc water and seawater. The survival rate showed the opposite trend to the growth rate. Immune related genes mRNA expression levels in the postlarvae in the biofloc water were significantly lower than those in the seawater. While, the adult stage showed significantly higher PO enzyme activations in the biofloc water than in the seawater with the PO enzyme activation increasing proportionally to the biofloc concentration. This result is considerably explained by the observations of setal morphological structures of the third maxilliped: postlarvae have short serrulated setae that compose the small 'net' structure while adults had long and dense plumose setae. It is understood that the morphological difference of the maxilliped structure resulted in the different feeding abilities in the postlarvae and the adult F. chinensis to use bioflocs as food source.

• 농업과학연구
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• 제50권3호
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• pp.395-406
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• 2023

The large amount of energy required for successful crop production is the main challenge in greenhouse cropping systems. As a response to this challenge a comprehensive evaluation of greenhouse energy consumption was carried out in two structurally similar single-span greenhouses with different thermal curtain positions, with particular attention to energy productivity, specific energy, net energy, and energy ratio. The greenhouses are used for strawberry production. In the R-greenhouse (RGH), the thermal curtain hanged directly at the roof ridge, whereas in the Q-greenhouse (QGH), the thermal curtain was placed 5° from an imaginary vertical axis, from the middle of the roof ridge downwards to the north side of the greenhouse roof. The relevant data were recorded using standard methods. The results indicated that the energy expended in the RGH and QGH systems was 2,186.48 and 2,189.26 MJ/m², respectively. Electricity and nitrogen fertilizer contributed the highest energy input in both greenhouses and in all seasons. The output energy was 3.12 and 3.82 MJ/m², respectively, in RGH and QGH in season I and 4.40 and 4.87 MJ/m² in season II. In terms of energy expended, there was no significant difference between the two greenhouses, nor between the two seasons. These results indicate that greenhouses of the size used in this investigation are not viable in terms of energy productivity, energy-use efficiency, and subsequent economic performance. However, further studies should be conducted to scale-up the information obtained from this investigation.

• Nuclear Engineering and Technology
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• 제56권5호
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• pp.1830-1835
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• 2024

The current study aims to study the impacts of the substitution of magnesium with nickel concentrations on physical and γ-ray shielding capacity of magnesium alloys. The density of the magnesium alloys under study is varied from 3.677 g/cm³ to 5.652 g/cm³, with raising the nickel content from 26.7 wt% to 54.8 wt% and reducing the magnesium concentration from 72.6 wt% to 44.2 wt%, respectively. Additionally, the examination of the γ-ray shielding capacity using the Monte Carlo simulation code shows that the substitution of magnesium by nickel content in the magnesium alloys was associated with an enhancement in the γ-ray shielding capacity, where the linear attenuation coefficient for the studied alloys was enhanced by 53.22 %, 52.45 %, and 52.52 % at γ-ray energies of 0.662 MeV, 1.252 MeV, and 1.408 MeV, respectively, with raising the nickel concentration from 26.7 wt% to 54.8 wt%. Simultaneously, the half-value thickness for magnesium alloys was reduced from 2.47 cm to 1.62 cm (at gamma ray energy of 0.662 MeV), from 3.39 cm to 2.22 cm (at gamma ray energy of 1.252 MeV), and from 3.60 cm to 2.36 cm (at gamma ray energy of 1.408 MeV), raising the nickel concentration from 26.7 wt % to 54.8 wt%, respectively. The study shows that the substitution of magnesium for nickel greatly enhanced the radiation shielding capacity of the magnesium alloys.

• 한국산림과학회지
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• 제105권4호
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• pp.510-516
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• 2016

본 연구는 실외 실험적 온난화 시스템 내에서 적외선등을 이용하여 온난화 처리를 한 다음 발아 당년의 활엽수 4개 수종(물푸레나무, 느티나무, 거제수나무, 굴참나무) 묘목의 생리적 반응을 알아보고자 수행되었다. 적외선등은 2015년 4월부터 가동되었으며, 온난화 처리구 내의 묘목들은 대조구에 비해 $2.7^{\circ}C$ 높은 대기온도 하에서 생육되었다. 기공전도도, 증산속도 및 순광합성률은 동년 7월과 9월에, 엽록소 함량은 7월과 10월에 각각 측정하였다. 온도 증가에 대한 묘목의 생리적 반응은 수종과 측정 시기에 따라 다른 결과를 나타내었다. 즉 기공전도도($mmol{\cdot}m^{-2}{\cdot}s^{-1}$)는 물푸레나무(대조구:$158.97{\pm}42.76$; 온난화 처리구:$42.07{\pm}8.24$), 느티나무(대조구:$170.53{\pm}27.22$; 온난화 처리구: $101.17{\pm}42.27$), 거제수나무(대조구:$249.93{\pm}47.39$; 온난화 처리구:$150.73{\pm}26.52$)에서 온난화 처리에 의해 감소하였다. 그리고 증산속도($mmol{\cdot}m^{-2}{\cdot}s^{-1}$)도 물푸레나무(대조구:$4.08{\pm}0.62$; 온난화 처리구:$1.74{\pm}0.39$), 느티나무(대조구:$4.32{\pm}0.44$; 온난화 처리구:$3.24{\pm}1.14$), 거제수나무(대조구:$6.21{\pm}0.38$; 온난화 처리구:$4.66{\pm}0.28$)에서 대조구에 비해 온난화 처리구에서 낮은 값을 나타내었다. 한편, 굴참나무의 경우 기공전도도와 증산속도의 처리 간 차이가 유의하지 않았다. 엽록소 함량은 대부분의 수종에서 온난화 처리에 의해 증가하였으나, 순광합성률은 모든 수종에서 처리 간의 차이가 통계적으로 유의하지 않았다. 이는 온난화 처리의 영향이 미미하여 순광합성률의 변화에까지 영향을 미치지 못하였기 때문인 것으로 판단된다.

• 한국해양학회지:바다
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• 제5권2호
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• pp.105-118
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• 2000

반폐쇄형의 함평만 입구를 가로지르는 두 개의 정점(H1, H2)에서 1999년 8월 12-13일 대조기에 각각 한 조석주기동안 물리적 특성과 부유퇴적물의 농도변화에 대한 정선관측을 실시하였다. 수온과 염분의 조석변화는 각각 26.0-27.9$^{\circ}C$, 30.9-31.5 범위에서 창조시 저온과 고염분의 외해수 그리고 낙조시 고온과 저염분의 연안수 특성을 보이며, 복사열이 강한 여름철임에도 불구하고 강한 조류의 혼합작용으로 인해 수괴의 수직적 혼합이 잘 이루어지고 있다. 부유퇴적물의 농도는 표층에서 낮고 저층으로 향하면서 높아지며 수층별로 뚜렷한 차이를 보이고 있다. 불량한 분급도를 보이는 부유퇴적물은 대부분 극세립- 세립실트(>40%)로 구성되어 있는 가운데, 점토 크기 이하(<4 ${\mu}m$)의 세립자들은 에너지가 약한 정조시에 상호간의 결합을 통해 입자 덩어리를 형성하고 있다. 조석별 평균유속의 세기는 남서쪽 정점 H1의 경우 낙조류가 창조류에 비해 수층에 따라 23-59${\%}$ 우세한 반면, 정점 H2에서는 오히려 창조류가낙조류에 비해 27-37${\%}$ 우세한 비대칭성을 보이고 있다. 이에 따른 각 정점에서 계산된 잔여유속은 정점 H1에서 아주 큰 값(-10${\sim}$-20 cm $s^{-1}$)으로 외해쪽으로 향하고 있는 반면, 정점 H2에서는 내만쪽으로 향하는 미약한 흐름(<5 cm $s^{-1}$)이 존재한다. 한편, 부유퇴적물의 농도변화는 남서쪽(H1)에서 낙조시에 비해 창조류를 따라 외해로부터 유입되는 양이 많고, 정점 H2에서는 창조시에 비해 낙조류를 따라 외해로 유출되는 양이 훨씬 높게 나타나고 있다. 잔여유속과 부유퇴적물의 농도를 고려한 부유퇴적물의 순이동률($f_{s}$)은 모든 정점에서 수층에 따라 -1.7 ${\sim}$-15.6${\times}$$10^{-3}$ kg $m^{-2}$ $s^{-1}$ 속도로 일관되게 외해쪽으로 향하고 있으며, 북동쪽에서 보다 빠른 이동률을 보이고 있다. 부유퇴적물의 순이동량($\c{Q}_{s}$)은 정점 H1과 H2에서 각각 0.37${\times}$$10^{3}$, 0.21${\times}$$10^{3}$ kg $m^{-1}$의 양이 여름철 대조기 한 조석주기동안에 외해로 빠져나가고 있는 것으로 나타났다. 함평만 입구에서 여름철임에도 불구하고 부유퇴적물이 외해쪽으로 이동되고 있는 것은 내만에 발달되어 있는 조간대의 침식을 의미하는 것으로서, 지금까지 서해안 조간대에서 보고되고 있는 일반적인 여름철 퇴적현상과는 상이한 결과를 나타내고 있다.

• 한국산림과학회지
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• 제90권4호
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• pp.476-487
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• 2001

본 연구는 내음수(耐陰樹)가 임상(林床)의 낮은 광도조건에 적응하는 기작을 구명하기 위해서, 양수(陽樹)와 내음수(耐陰樹)의 생육 광도 저하에 대한 광합성계(光合成系)의 적응반응을 서로 비교하였다. 이태리포플러, 음나무, 졸참나무 1년생 묘목을 대상으로 PPFD $920{\mu}mol\;m^{-2}s^{-1}$과 PPFD $80{\mu}mol\;m^{-2}s^{-1}$의 광도조건에서 5개월간 생장한 개체의 엽록소함량, 잎의 분광특성, 광합성특성 등을 조사하였다. 그 결과 양수인 이태리포플러는 생육 광도의 저하로 엽면적, 단위 엽면적 당의 엽록소함량, 빛의 흡수율 및 광합성에 대한 이용효율 등이 감소하고, 광합성의 광화학계 및 탄소고정계의 활성 저하로 낮은 광합성능력을 나타냈다. 그러나 내음성이 이태리포플러보다 강한 음나무와 졸참나무는 엽면적, 엽록소함량, 순양자수율을 증가시켜 빛의 흡수량과 광합성에 대한 이용효율을 높이는 적응반응을 나타냈다. 그리고 이들 수종은 낮은 광도에서도 광합성의 광화학계 및 탄소고정계의 활성이 정상적으로 유지되고 있음을 알 수 있었다.

• Asian-Australasian Journal of Animal Sciences
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• 제23권1호
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• pp.74-81
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• 2010

The effects of different levels of natural clay enterosorbent on the growth, nutrient availability, and genital organs of post-weaning female pigs fed with an addition of zearalenone (ZEA) were investigated in the study. A total of thirty-five post-weaning gilts ($L{\times}Y{\times}D$) with an average body weight of 12.36${\pm}$1.46 kg were used in the test. The gilts were raised individually in metabolism cages and fed a corn-soybean meal-whey basal diet with an addition of 0 or 1 mg/kg of ZEA for 24 d with four levels of natural clay enterosorbent added in the feed. The treatments were: i) control; ii) control+2.5 g/kg clay; iii) control+1 mg/kg ZEA; iv) control+1 mg/kg ZEA+1.25 g/kg clay; v) control+1 mg/kg ZEA+2.5 g/kg clay; vi) control+1 mg/kg ZEA+5.0 g/kg clay; vii) control+1 mg/kg ZEA +10 g/kg clay. Pigs fed diets contaminated with additional purified ZEA had significantly reduced apparent digestibility of crude protein (CP), gross energy (GE) and apparent metabolic rate of GE (ME/GE, p<0.05) without changes of net protein utilization (NPU, p>0.05). Final body weight, average daily gain (ADG), average daily feed intake (ADFI), vulva length, vulva width, vulva area, relative weights of genital organ and proliferative changes of the ovary tissues in gilts fed ZEA-contaminated diet were increased (p<0.05) compared to the gilts fed the control diet. Addition of natural clay enterosorbent in the ZEA-contaminated diet showed a positive protection effect on ZEA feeding, and the protection was increased linearly or quadratically as clay content increased. However, in pigs fed a diet with clay alone at 2.5 g/kg level there was no significant impact (p>0.05) on all the parameters as compared to the control. It is suggested that feeding ZEA at about 1.0 mg/kg for 24 days might result in a deleterious effect in pigs, and addition of 5 or 10 g clay enterosorbent per kg diet can effectively neutralize the detrimental effects of the ZEA feeding.