• Journal of Electrochemical Science and Technology
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• 제13권3호
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• pp.390-397
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• 2022

The use of microwaves as the energy source for synthesis and sintering of ceramics offers substantial advantages compared to conventional gas-fired and electric resistance furnaces. Benefits include much shorter processing times and reaching the sintering temperature more quickly, resulting in superior final product quality. Most oxide ceramics poorly interact with microwave irradiation at low temperatures; thus, a more complex setup including a susceptor is needed, which makes the whole process very complicated. This investigation pursued a new approach, which enabled us to use microwave irradiation directly in poorly coupled oxides. In many solid-state electrochemical devices, the support is either metal or can be reduced to metal. Metal powders in the support can act as an internal susceptor and heat the entire cell. Then sufficient interaction of microwave irradiation and ceramic material can occur as the sample temperature increases. This microwave heating and exothermic reaction of oxidation of the support can sinter the ceramic very efficiently without any external susceptor. In this study, yttria stabilized zirconia (YSZ) and a Ni-YSZ cermet support were used as an example. The cermet was used as the support, and a YSZ electrolyte was coated and sintered directly using microwave irradiation without the use of any susceptor. The results were compared to a similar cell prepared using a conventional electric furnace. The leakage test and full cell power measurement results revealed a fully leak-free electrolyte. Scanning electron microscopy and density measurements show that microwave sintered samples have lower open porosity in the electrode support than conventional heat treatment. This technique offers an efficient way to directly use microwave irradiation to sinter thin film ceramics without a susceptor.

• 한국식품과학회지
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• 제16권1호
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• pp.66-70
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• 1984

방사선(放射線) 조사(照射)와 자연저온(自然低溫)에 의한 마늘의 상업적(商業的) 저장법(貯藏法) 개발(開發)을 목표(目標)로 수확후(收穫後) 1개월(個月)된 시료(試料)에 $^{60}Co\;{\gamma}-$선(線)을 50, 100 및 150Gy 조사(照射)시킨 뒤 자연저온(自然低溫) 저장고(貯藏庫) $(12{\pm}6^{\circ}C,\;75{\sim}85%RH)$에 10개월(個月) 동안 저장(貯藏)하면서 이화학적(理化學的) 특성(特性)을 검토(檢討)하였다. 비조사구(非照射區)는 저장(貯藏) 8개월(個月) 후(後)에 대부분 발아(發芽)되었으나 조사구(照射구區)는 저장(貯藏) 10개월(個月) 까지도 전혀 외부 발아(發芽)되지 않았다. 저장(貯藏) 10개월(個月) 후(後) 부패율(腐敗率)은 비조사구(非照射區)가 83.56%, 조사구(照射區)가 약(約) 29%로 ${\gamma}-$선(線) 조사(照射)로서 54%의 부패율(腐敗率)을 감소(減少)시킬 수 있었고, 중량변화(重量變化)에 있어서도 ${\gamma}-$선(線) 조사(照射)에 의하여 약(約) 25%의 감량(減量)을 막을 수 있었다. 저장중(貯藏中) 수분함량(水分含量)은 큰 변화(變化)가 없었으나 발아(發芽)와 더불어 다소 감소(減少)되었고, 전당(全糖)과 환원당(還元糖)은 저장기간(貯藏期間)의 경과로 각각 증감현상(增減現象)이 나타났으며, 특(特)히 발아(發芽)가 왕성(旺盛)한 이듬해 3월(月)부터는 그 변화(變化)가 두드러졌다. 또한 ascorbic acid 함량(含量)은 기간(期間)의 경과로 점차 감소(減少)하다가 발아(發芽)와 더불어 증가(增加)되었다. 따라서 수확후(收穫後) 마늘에 100Gy 정도의 ${\gamma}$-선(線)을 조사(照射)하여 $10^{\circ}C$ 내외(內外)의 자연저온(自然低溫) 저장고(貯藏庫)에 저장(貯藏)함으로써 그 품질(品質)을 비교적(比較的) 우수(優秀)하게 10개월(個月) 이상(以上) 보존(保存)할 수 있었다.

• 한국식품과학회지
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• 제31권4호
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• pp.1050-1056
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• 1999

식품첨가제의 사용없이도 저장성과 향미특성이 우수한 저염 오징어젓갈을 개발하기 위한 방법으로 감마선 조사기술을 이용하였다. 식염농도를 각각 5%, 10%, 20%로 조절한 오징어젓에 감마선을 조사한 후 $15^{\circ}C$와 $25^{\circ}C$에서 발효시키면서 일반성분, 식염함량, 수분활성도, pH, 총균수 및 관능적 품질 변화를 조사하였다. 감마선 조사직후 또는 발효기간 중 일반성분과 식염함량 및 수분활성은 감마선 조사에 의해 영향을 받지 않았다. 오징어젓갈의 총균수와 pH는 식염농도와 감마선 조사선량 및 발효온도에 따라 영향을 받았으며, 10%의 식염 첨가와 10 kGy의 감마선 조사를 병용처리한 오징어젓을 $15^{\circ}C$에서 발효시킨 경우 비조사구에 비해 적절한 미생물의 생육 저해로 저장기간 연장 효과를 보였고, 30일까지 관능적 품질이 적합하게 유지되는 것으로 나타났다.

• Nuclear Engineering and Technology
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• 제54권8호
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• pp.2792-2800
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• 2022

In the core of the WWR-K reactor, a long-term irradiation of tristructural isotopic (TRISO)-coated fuel particles (CFPs) with a UO₂ kernel was carried out under high-temperature gas-cooled reactor (HTGR)-like operating conditions. The temperature of this TRISO fuel during irradiation varied in the range of 950-1100 ℃. A fission per initial metal atom (FIMA) of uranium burnup of 9.9% was reached. The release of gaseous fission products was measured in-pile. The release-to-birth ratio (R/B) for the fission product isotopes was calculated. Aspects of fuel safety while achieving deep fuel burnup are important and relevant, including maintaining the integrity of the fuel coatings. The main mechanisms of fuel failure are kernel migration, silicon carbide corrosion by palladium, and gas pressure increase inside the CFP. The formation of gaseous fission products and carbon monoxide leads to an increase in the internal pressure in the CFP, which is a dominant failure mechanism of the coatings under this level of burnup. Irradiated fuel compacts were subjected to electric dissociation to isolate the CFPs from the fuel compacts. In addition, nondestructive methods, such as X-ray radiography and gamma spectrometry, were used. The predicted R/B ratio was evaluated using the fission gas release model developed in the high-temperature test reactor (HTTR) project. In the model, both the through-coatings of failed CFPs and as-fabricated uranium contamination were assumed to be sources of the fission gas. The obtained R/B ratio for gaseous fission products allows the finalization and validation of the model for the release of fission products from the CFPs and fuel compacts. The success of the integrity of TRISO fuel irradiated at approximately 9.9% FIMA was demonstrated. A low fuel failure fraction and R/B ratios indicated good performance and reliability of the studied TRISO fuel.

• 전기학회논문지
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• 제56권11호
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• pp.1972-1977
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• 2007

Micro plasma has been recently studied to investigate the effects on various cells. We study a micro-plasma produced by a plasma needle that is operated with RF power and its effects on G361 melanoma cells. The micro plasma size ranges from sub-mm to several mm at a few watts of RF power. For the bio-medical treatment, low-temperature plasma is obtained and gas temperature is controlled within several tens of degrees $(^{\circ}C)$ in order not to disturb cell activities. Elementary spectroscopic studies to obtain plasma characteristics are presented for Ar and He plasma with different frequencies of RF power. Also the preliminary results of the micro plasma effects on G361 melanoma cells are presented. It was observed that the irradiation of micro plasma induces cell death through the deprivation of tyrosine phosphorylation in the G361 cells.

• Current Research on Agriculture and Life Sciences
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• 제3권
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• pp.79-84
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• 1985

저장상 많은 문제점을 내포하고 있는 감자, 양파, 마늘 및 밤의 장기 저장법 개발을 목적으로 수확후 l개월 이내에 Co-60 감마선을 조사하고 냉동기를 가동하지 않은 자연저온 저장고에 각각 저장하였다. 저장중 시료의 발아는 감자가 150Gy, 양파 및 마늘이 50Gy 밤이 250 Gy의 선량으로 8~10개월간 거의 완전히 억제되었다. 감마선 조사에 따라 부패율은 상당히 감소되었으며, 중량감소에 있어서도 적정선량의 조사는 네가지 사료에서 6~24%의 감소 억제 효과를 나타내었다. 발아식품의 품질에 관여하는 성분인 수분, 당 및 비타민 C의 함량은 저장기간의 경과로 비조사구에 비해 조사구가 우수한 경향을 보였다. 따라서 이들 식품의 장기 안전저장을 위해서는 감자, 양파 및 마늘은 50~150 Gy, 밤은 250 Gy 정도의 감마선을 조사하고 자연저온저장고($10{\pm}5^{\circ}C$ R.H. 75~85%)에저장하는 것이 효과적인 방법임을 시사하였다.

• Nuclear Engineering and Technology
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• 제33권4호
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• pp.365-374
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• 2001

In order to examine the in-reactor performance of very-high-density dispersion fuels for high flux performance research reactors, U-l0wt.%Mo microplates containing centrifugally atomized powder were irradiated at low temperature. The U-l0wt.%Mo dispersion fuels show stable in- reactor irradiation behaviors even at high burn-up, similar to U$_3$Si$_2$ dispersion fuels. The atomized U-l0wt.%Mo fuel particles have a fine and a relatively uniform fission gas bubble size distribution. Moreover, only one of third of the area of the atomized fuel cross-sections at 70a1.% burn-up shows fission gas bubble-free zones, This appears to be the result of segregation into high Mo and low Mo.

• 한국압력기기공학회 논문집
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• 제10권1호
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• pp.113-121
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• 2014

In this work, an integrated model including molecular dynamics and chemical rate theory was implemented to calculate the growth of point defect clusters(PDC) and copper-rich precipitates(CRP) which could change the mechanical properties of reactor pressure vessel(RPV) steels in a nuclear power plant. A number of time-dependent differential equations were established and numerically integrated to estimate the evolution of irradiation defects. The calculation showed that the concentration of the vacancies was higher than that of the self-interstitial atoms. The higher concentration of vacancies induced a formation of the CRPs in the later stage. The size of the CRPs was used to estimate the mechanical property changes in RPV steels, as is the same case with the PDCs. The calculation results were compared with the measured values of yield strength change and Charpy V-notch transition temperature shift, which were obtained from the surveillance test data of Korean light water reactors(LWRs). The estimated values were in fair agreement with the experimental results in spite of the uncertainty of the modeling parameters.

• Nuclear Engineering and Technology
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• 제45권2호
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• pp.219-222
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• 2013

Alloy 690 has been selected as a steam generator tubing material for SMART owing to a near immunity to primary water stress corrosion cracking. The steam generators of SMART are faced with a neutron flux due to the integrated arrangement inside a reactor vessel, and thus it is important to know the irradiation effects of the thermal conductivity of Alloy 690. Alloy 690 was irradiated at HANARO to fluences of (0.7-28) ${\times}10^{19}n/cm^2$ (E>0.1MeV) at $250^{\circ}C$, and its thermal conductivity was measured using the laser-flash equipment in the IMEF. The thermal conductivity of Alloy 690 was dependent on temperature, and it was a good fit to the Smith-Palmer equation, which modified the Wiedemann-Franz law. The irradiation at $250^{\circ}C$ did not degrade the thermal conductivity of Alloy 690, and even showed a small increase (1%) at fluences of (0.7~28) ${\times}10^{19}n/cm^2$ (E>0.1MeV).

• 한국압력기기공학회 논문집
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• 제16권2호
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• pp.58-67
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• 2020

This study presents cyclic stress-strain and tensile test results at room temperature (RT) and 316℃ using cold-worked TP304 stainless steel base and weld metals. By comparing the cyclic hardening/softening behavior and failure cycle of cold-worked materials with those of irradiated austenitic stainless steels, the feasibility of simulating the irradiation effect on cyclic deformation and failure behaviors of TP304 stainless steel base and weld metals was investigated. It was found that, in the absence of strain-induced martensite trasformation, cold-working could properly simulate the change in cyclic hardening/softening behavior of TP304 stainless steel base and weld metals due to neutron irradiation. It was also recognized that cold-working could adequately simulate the reduction in failure cycles of TP304 stainless steel base and weld metals due to neutron irradition in the low-cycle fatigue region.