• Nuclear Engineering and Technology
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• 제49권5호
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• pp.1044-1062
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• 2017

The construction project of the Kijang research reactor (KJRR), which is the second research reactor in Korea, has been launched. The KJRR was designed to use, for the first time, U-Mo fuel. Plate-type U-7 wt.% Mo/Al-5 wt.% Si, referred to as U-7Mo/Ale5Si, dispersion fuel with a uranium loading of $8.0gU/cm^3$, was selected to achieve higher fuel efficiency and performance than are possible when using $U_3Si_2/Al$ dispersion fuel. To qualify the U-Mo fuel in terms of plate geometry, the first miniplates [HANARO Miniplate (HAMP-1)], containing U-7Mo/Al-5Si dispersion fuel ($8gU/cm^3$), were fabricated at the Korea Atomic Energy Research Institute and recently irradiated at HANARO. The PIE (Post-irradiation Examination) results of the HAMP-1 irradiation test were analyzed in depth in order to verify the safe in-pile performance of the U-7Mo/Al-5Si dispersion fuel under the KJRR irradiation conditions. Nondestructive analyses included visual inspection, gamma spectrometric mapping, and two-dimensional measurements of the plate thickness and oxide thickness. Destructive PIE work was also carried out, focusing on characterization of the microstructural behavior using optical microscopy and scanning electron microscopy. Electron probe microanalysis was also used to measure the elemental concentrations in the interaction layer formed between the U-Mo kernels and the matrix. A blistering threshold test and a bending test were performed on the irradiated HAMP-1 miniplates that were saved from the destructive tests. Swelling evaluation of the U-Mo fuel was also conducted using two methods: plate thickness measurement and meat thickness measurement.

• Nuclear Engineering and Technology
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• 제55권4호
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• pp.1460-1467
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• 2023

A robust approach was conducted to determining the absolute oral bioavailable (f_ab) fractions of ²³⁸U and ²³²Th in rats exposed to contaminated soil along with their hematotoxicity and nephrotoxicity. The soil sample is the International Atomic Energy Agency-312 (IAEA-312) certified reference material, whereas blood, bones, and kidneys of in vivo female Sprague-Dawley (SD) rats estimate ²³⁸U- and ²³²Th-f_ab fractions post-exposure. We predict the bioavailable concentration (C_ab) and f_ab values of ²³⁸U and ²³²Th after acute soil ingestion. The blood ²³⁸U (0.750%) and ²³²Th (0.028%) reach their maximum f_ab values after 48 h. The ²³⁸U (f_ab: 0.169-0.652%) accumulates mostly in the kidney, whereas the ²³²Th (f_ab: 0.004-0.021%) accumulates primarily in the bone. Additionally, ²³⁸U is more bioavailable than ²³²Th. Post 48 h acute ingestion demonstrates noticeable histopathological and hematological alterations, implying that intake of ²³⁸U in co-contaminated soil can lead to erythrocytes and proximal tubules damage, whereas, ²³²Th intake can harm erythrocytes. Our study provides new directions for future research into the health implications of acute oral exposures to ²³⁸U and ²³²Th in co-contaminated soils. The findings offer significant insight into the utilization of in vivo SD rat testing to estimate ²³⁸U and ²³²Th bioavailability and toxicity in exposure assessment.

• Nuclear Engineering and Technology
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• 제44권3호
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• pp.225-236
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• 2012

The Fukushima-Daiichi accident shook the world, as a well-known plant design, the General Electric BWR Mark I, was heavily damaged in the tsunami, which followed the Great Japanese Earthquake of 11 March 2011. Plant safety functions were lost and, as both AC and DC failed, manoeuvrability of the plants at the site virtually came to a full stop. The traditional system of Emergency Operating Procedures (EOPs) and Severe Accident Management Guidelines (SAMG) failed to protect core and containment, and severe core damage resulted, followed by devastating hydrogen explosions and, finally, considerable radioactive releases. The root cause may not only have been that the design against tsunamis was incorrect, but that the defence against accidents in most power plants is based on traditional assumptions, such as Large Break LOCA as the limiting event, whereas there is no engineered design against severe accidents in most plants. Accidents beyond the licensed design basis have hardly been considered in the various designs, and if they were included, they often were not classified for their safety role, as most system safety classifications considered only design basis accidents. It is, hence, time to again consider the Design Basis Accident, and ask ourselves whether the time has not come to consider engineered safety functions to mitigate core damage accidents. Associated is a proper classification of those systems that do the job. Also associated are safety criteria, which so far are only related to 'public health and safety'; in reality, nuclear accidents cause few casualties, but create immense economical and societal effects-for which there are no criteria to be met. Severe accidents create an environment far surpassing the imagination of those who developed EOPs and SAMG, most of which was developed after Three Mile Island - an accident where all was still in place, except the insight in the event was lost. It requires fundamental changes in our present safety approach and safety thinking and, hence, also in our EOPs and SAMG, in order to prevent future 'Fukushimas'.

• 한국어류학회지
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• 제32권2호
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• pp.97-102
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• 2020

거제시 구조라 및 망치 연안에서 우점하여 출현한 까나리(Ammodytes japonicus) 자어는 조사기간인 2019년 1월과 2월 동안 총 208개체가 채집되었고 척생장의 범위는 1.46~8.00 mm였다. 까나리 자어의 주먹이생물은 요각류가 가장 우점하였고, 그 중 긴노요각목 요각류를 가장 많이 섭식하였으며, 검물벼룩목 요각류를 그 다음으로 많이 섭식하였다. 요각류 외에도 어류 난, 패충류, 갑각류 유생도 섭식하였으나 그 양은 많지 않았다. 까나리 자어의 성장에 따른 먹이생물 변화양상을 알아보기 위해 3개의 크기군으로 나누어 분석한 결과(≤2 mm, 3~4 mm, ≥5 mm, Notochord length), 성장함에 따라 긴 노요각목 요각류의 섭식비율은 점차 증가하고 검물벼룩목 요각류는 감소하였으며, 평균 먹이생물의 개체수와 부피 모두 증가하는 경향이 나타났다.

• Nuclear Engineering and Technology
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• 제49권7호
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• pp.1442-1450
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• 2017

In liquid metal fast breeder reactors, postulated failures of the plant protection system may lead to serious unprotected accidental consequences. Unprotected transients are generically categorized as transient overpower accidents and transient under cooling accidents. In both cases, core meltdown may occur and this can lead to a molten fuel coolant interaction (MFCI). The understanding of MFCI phenomena is essential for study of debris coolability and characteristics during post-accident heat removal. Sodium is used as coolant in liquid metal fast breeder reactors. Viewing inside sodium at elevated temperature is impossible because of its opaqueness. In the present study, a methodology to depict MFCI phenomena using a flat panel detector based imaging system (i.e., real time radiography) is brought out using a woods metal-water experimental facility which simulates the $UO_2-Na$ interaction. The developed imaging system can capture attributes of the MFCI process like jet breakup length, jet front velocity, fragmented particle size, and a profile of the debris bed using digital image processing methods like image filtering, segmentation, and edge detection. This paper describes the MFCI process and developed imaging methodology to capture MFCI attributes which are directly related to the safe aspects of a sodium fast reactor.

• 농업과학연구
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• 제45권3호
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• pp.325-353
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• 2018

Agricultural systems in South Asian countries are dominated by smallholder farmers. Additionally, these farmers have limited access to pre- and post-harvest technologies due to their high initial cost. The lack of these technologies in postharvest handling is responsible for 20% to 44% of fruit and vegetable losses. These high losses are largely the result of a generally weak basic postharvest infrastructure for the preservation of products, which avoids damage from improper handling, transportation, packaging, and storage. High postharvest losses of products negatively affect food availability, food security, and nutrition, as the producer is able to sell less of the farm yield and the net availability of these food commodities for consumption is reduced. An underlying cause of these postharvest losses is the limited awareness and knowledge bases of stakeholders (researchers, farmers, governments, non-governmental organizations, and merchants) in the traditional supply chains in which these losses occur. The analysis presented in this paper explores the state of postharvest practice in South Asian countries and discusses options for low-cost postharvest technologies in the region that can support small-scale farmers and provide a viable pathway for supply to the market, joining with modern value chains and bringing about individual and regional reduction in postharvest losses of fruits and vegetables. The improvement of basic and simple low-cost technologies through precise research efforts has the potential to prevent such huge losses of products, and help meet the ever-increasing demand for food in South Asian countries.

• 터널과지하공간
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• 제20권3호
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• pp.207-216
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• 2010

국내에서 현재까지 개발되어 적용된 낙석감지 시스템은 주로 낙석방지망에 와이어나 광섬유, 또는 경사계를 설치하여 와이어의 장력을 측정하거나 낙석 발생에 의해 와이어 단락이나 낙석방지망의 변형 또는 기울어지는 것을 감지하여 낙석을 확인하는 시스템들이다. 이러한 방법들은 낙석방지망이 먼저 설치되어 있어야 하며 낙석이 발생하면 일반적으로 관련 센서와 와이어 등에 대하여 재정비를 해야 다시 원래의 기능을 수행할 수 있게 된다. 이러한 단점을 해결하기 위하여 본 연구에서는 장력이나 변위 측정방식이 아니라 광센서와 카메라가 설치된 구역에서 낙석 통과 여부를 비접촉 방식으로 실시간 감지가 가능하도록 하는 방법을 제시하고 이를 구현하였다. 개발된 시스템을 실내실험 및 현장 적용을 한 결과 낙석 관련 정보를 효과적으로 수집하고 분석할 수 있었다. 또한 낙석 감지 전후 획득한 2장의 사진에 대하여 lighten 또는 difference 연산을 적용할 경우 낙석의 크기와 이동 방향에 대한 개략적 평가가 가능하였다.

• Nuclear Engineering and Technology
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• 제52권3호
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• pp.597-609
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• 2020

Accident Tolerant Fuels have been widely studied since the Fukushima-Daiichi accident in 2011 as one of the options on how to further enhance the safety of nuclear power plants. Deposition of protective coatings on nuclear fuel claddings has been considered as a near-term concept that will reduce the high-temperature oxidation rate and enhance accidental tolerance of the cladding while providing additional benefits during normal operation and transients. This study focuses on experimental testing of Zr-based alloys coated with Cr-based coatings using Physical Vapour Deposition. The results of long-term corrosion tests, as well as tests simulating postulated accidents, are presented. Zr-1%Nb alloy used as nuclear fuel cladding serves as a substrate and Cr, CrN, Cr_xN_y layers are deposited by unbalanced magnetron sputtering and reactive magnetron sputtering. The deposition procedures are optimized in order to improve coating properties. Coated as well as reference uncoated samples were experimentally tested. The presented results include standard long-term corrosion tests at 360℃ in WWER water chemistry, burst (creep) tests and mainly single and double-sided high-temperature steam oxidation tests between 1000 and 1400℃ related to postulated Loss-of-coolant accident and Design extension conditions. Coated and reference samples were characterized pre- and post-testing using mechanical testing (microhardness, ring compression test), Thermal Evolved Gas Analysis analysis (hydrogen, oxygen concentration), optical microscopy, scanning electron microscopy (EDS, WDS, EBSD) and X-ray diffraction.

• Molecules and Cells
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• 제25권2호
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• pp.265-271
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• 2008

Single nucleotide polymorphisms (SNPs) are the most common form of human genetic variation. Non-synonymous SNPs (nsSNPs) change an amino acid. Organic anion transporters (OATs) play an important role in eliminating or reabsorbing endogenous and exogenous organic anionic compounds. Among OATs, hOAT4 mediates high affinity transport of estrone sulfate and dehydroepiandrosterone sulfate. The rapid bone loss that occurs in post-menopausal women is mainly due to a net decrease of estrogen. In the present study we searched for SNPs within the exon regions of hOAT4 in Korean women osteoporosis patients. Fifty healthy subjects and 50 subjects with osteoporosis were screened for genetic polymorphism in the coding region of SLC22A11 (hOAT4) using GC-clamp PCR and denaturing gradient gel electrophoresis (DGGE). We found three SNPs in the hOAT4 gene. Two were in the osteoporosis group (C483A and G832A) and one in the normal group (C847T). One of the SNPs, G832A, is an nsSNP that changes the $278^{th}$ amino acid from glutamic acid to lysine (E278K). Uptake of [$3^H$] estrone sulfate by oocytes injected with the hOAT4 E278K mutant was reduced compared with wild-type hOAT4. Km values for wild type and E278K were $0.7{\mu}M$ and $1.2{\mu}M$, and Vmax values were 1.8 and 0.47 pmol/oocyte/h, respectively. The present study demonstrates that hOAT4 variants can causing inter-individual variation in anionic drug uptake and, therefore, could be used as markers for certain diseases including osteoporosis.

• 한국전자거래학회지
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• 제25권1호
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• pp.177-202
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• 2020

본 연구는 세계 무기 수출 시장의 구조적인 변화 요인을 식별하기 위한 통계적 모형을 설계하고 실증 분석 결과와 경제적 함의를 제시하고자 한다. 무기 수출의 변화 양상을 설명할 수 있는 변인은 무엇인가, 그러한 변화는 통계적으로 유의한가, 변화의 특성은 어떻게 해석될 수 있는지를 중심으로 연구 질문을 삼고 분석의 틀을 설계하였다. 실증 분석을 위해 SIPRI 데이터베이스에 수록된 무기 수출 상위 40개 국가의 거래량을 분석 대상으로 삼았다. 그리고 연구 모형을 설정하기 위한 가설을 제시하고 가설로부터 도출된 변수들의 조합에 따라 여러 회귀 모형을 구성하여 통계적 유의성을 검증하였다. 분석 결과에서 국가 보유고 변수는 무기 수출 시장의 변화와 지속적인 관계를 맺고 있는 변수로서 특징적인 의미를 보여주고 있으며, UN 안보리 상임이사국 그룹은 세계 무기 수출에 집단적인 지배력을 발휘하고 있는 것으로 나타났다. 이와 함께 2000년대를 전후로 하여 나타난 변화의 주요 동인은 국내 총생산과 국가 순 수출액과 관련이 있는 것으로 파악되었다. 전반적으로 이런 요인들이 세계 무기 수출의 흐름과 방향을 좌우해왔던 것으로 평가되며 향후에도 무기 수출 시장의 구조에 영향을 주는 변수가 될 것으로 전망된다.