• Parasites, Hosts and Diseases
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• 제47권2호
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• pp.139-144
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• 2009

The aim of the present study was to investigate antimalarial drug pressure resulting from the clinical use of different antimalarials in Thailand. The phenotypic diversity of the susceptibility profiles of antimalarials, i.e., chloroquine (CQ), quinine (QN), mefloquine (MQ), and artesunate (ARS) in Plasmodium falciparum isolates collected during the period from 1988 to 2003 were studied. P. falciparum isolates from infected patients were collected from the Thai-Cambodian border area at different time periods (1988-1989, 1991-1992, and 2003), during which 3 different patterns of drug use had been implemented: MQ+sulphadoxine (S)+pyrimethamine (P), MQ alone and MQ+ARS, respectively. The in vitro drug susceptibilities were investigated using a method based on the incorporation of $[^3H]$ hypoxanthine. A total of 50 isolates were tested for susceptibilities to CQ, QN, MQ, and ARS. Of these isolates, 19, 16, and 15 were adapted during the periods 1988-1989, 1991-1993, and 2003, respectively. P. falciparum isolates collected during the 3 periods were resistant to CQ. Sensitivities to MQ declined from 1988 to 2003. In contrast, the parasite was sensitive to QN, and similar sensitivity profile patterns were observed during the 3 time periods. There was a significantly positive but weak correlation between the $IC_{50}$ values of CQ and QN, as well as between the $IC_{50}$, values of QN and MQ. Drug pressure has impact on sensitivity of P. falciparum to MQ. A combination therapy of MQ and ARS is being applied to reduce the parasite resistance, and also increasing the efficacy of the drug.

• Journal of Ecology and Environment
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• 제29권6호
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• pp.581-584
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• 2006

냉온대림의 주요 구성종으로 산지에도 분포하며 정원수로도 식재되고 있는 느티나무와 자작나무 그리고 미국에서 도입되어 조경수로 많이 활용되는 백합나무에서 내건성과 관련한 식물의 조직 수분 특성을 비교하였다. 한계원형질분리가 일어나는 점에서의 삼투포텐셜은 느티나무에서 -2.54 MPa로 가장 낮은 값을 나타내었으며, 백합나무에서 -2.03 MPa로 가장 높은 값을 나타내었다. 잎의 수분포텐셜 변화에 대한 압력 포텐셜의 변화에서도 느티나무가 가장 논은 압력포텐셜을 유지하였다. 세포의 자유수 함량 저하에 대한 압력포텐셜 변화 곡선은 전체적으로는 비슷한 패턴의 곡선을 나타내었지만 세포의 자유수 감소 시, 느티나무와 자작나무는 백합나무보다 높은 압력포텐셜을 유지하였다. 따라서 이들 세 종 중에서는 백합나무가 내건성이 가장 낮았으며, 느티나무는 다른 두 종에 비해 내건성이 가장 강하였다.

• 한국표면공학회지
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• 제56권6호
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• pp.401-411
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• 2023

This study investigates the synthesis, characterization, and application of zinc oxide (ZnO) nanoparticles for corrosion resistance and stress corrosion cracking (SCC) mitigation in high-temperature and high-pressure environments. The ZnO nanoparticles are synthesized using plasma discharge in water, resulting in rod-shaped particles with a hexagonal crystal structure. The ZnO nanoparticles are applied to Alloy 600 tubes in simulated nuclear power plant atmospheres to evaluate their effectiveness. X-ray diffraction and X-ray photoelectron spectroscopy analysis reveals the formation of thermodynamically stable ZnCr₂O₄and ZnFe₂O₄ spinel phases with a depth of approximately 35 nm on the surface after 240 hours of treatment. Stress corrosion cracking (SCC) mitigation experiments reveal that ZnO treatment enhances thermal and mechanical stability. The ZnO-treated specimens exhibit increased maximum temperature tolerance up to 310 ℃ and higher-pressure resistance up to 60 bar compared to non-treated ZnO samples. Measurements of crack length indicate reduced crack propagation in ZnO-treated specimens. The formation of thermodynamically stable Zn spinel structures on the surface of Alloy 600 and the subsequent improvements in surface properties contribute to the enhanced durability and performance of the material in challenging high-temperature and high-pressure environments. These findings have significant implications for the development of corrosion-resistant materials and the mitigation of stress corrosion cracking in various industries.

• 한국압력기기공학회 논문집
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• 제20권1호
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• pp.39-48
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• 2024

Research reactors are operated under ambient temperature and atmospheric pressure, which is much less severe conditions compared to those in typical nuclear power plants. Due to the high temperature, heat resistant materials such as austenite stainless steel should be used for the reactors in typical nuclear power plants. Whereas, as the effect of temperature is low for research reactors, materials with high resistance to neutron irradiation, such as zircaloy and beryllium, are used. Therefore, these conditions should be considered when performing integrity assessment for research reactors. In this study, a computational technique through finite element (FE) analysis was developed considering the operating conditions and materials of research reactor when conducting integrity assessment. Neutron irradiation analysis techniques using thermal expansion analysis were proposed to consider neutron irradiation growth and swelling in zirconium alloys and beryllium. A user subroutine program that can calculate the strain rate induced by neutron irradiation creep was developed for use in the commercial analysis program Abaqus. To validate the proposed technique and the user subroutine, FE analysis results were compared with hand-calculation results, and showed good agreement. Consequently, developed technique and user subroutine are suitable for evaluating structural integrity of research reactors.

• Spatial Information Research
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• 제23권5호
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• pp.75-85
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• 2015

최근 국지적 강품 및 태풍에 의한 방음벽의 변형 또는 파괴가 증가하고 있다. 본 연구에서는 1:5,000 수치지형도를 바탕으로 공간정보분석을 이용하여 방음벽의 설계풍하중 산정방법을 제시하였으며 실제 적용사례와 비교분석 하였다. GIS를 이용한 정량적인 평가 결과 건축물이 밀집한 도심지 구간은 지표조도가 III으로, 건물이 상대적으로 적은 교외지역에서는 지표조도가 II로, 개활지와 전형적인 농가밀집 지역은 지표조도가 I로 판정되는 등 실제 지표의 상태를 반영한 방음벽의 풍하중을 산정 할 수 있었다. 본 연구에서 제시한 정량적인 GIS 분석을 방음벽의 내풍설계에 반영한다면, 설계자의 주관에 따라 풍하중이 변화되는 기존의 문제점을 완화하여 보다 합리적인 내풍설계가 이루어 질 수 있을 것으로 판단된다.

• Journal of Nutrition and Health
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• 제50권3호
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• pp.217-224
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• 2017

Purpose: Although it is well known thatmortality and morbidity due to cardiovascular diseases are higher in salt-sensitive subjects than in salt-resistant subjects, their underlying mechanisms related to obesity remain unclear. Here, we focused on salt-sensitive gene variants unrelated to monogenic obesity that interacted with sodium intake in humans. Methods: This review was written based on the modified $3^rd$ step of Khans' systematic review. Instead of the literature, subject genes were based on candidate genes screened from our preliminary Genome-Wide Association Study (GWAS). Finally, literature related to five genes strongly associated with salt sensitivity were analyzed to elucidate the mechanism of obesity. Results: Salt sensitivity is a measure of how blood pressure responds to salt intake, and people are either salt-sensitive or salt-resistant. Otherwise, dietary sodium restriction may not be beneficial for everyone since salt sensitivity may be associated with inherited susceptibility. According to our previous GWAS studies, 10 candidate genes and 11 single nucleotide polymorphisms (SNPs) associated with salt sensitivity were suggested, including angiotensin converting enzyme (ACE), ${\alpha}$-adducin1 (ADD1), angiotensinogen (AGT), cytochrome P450 family 11-subfamily ${\beta}$-2 ($CYP11{\beta}$-2), epithelial sodium channel (ENaC), G-protein b3 subunit (GNB3), G protein-coupled receptor kinases type 4 (GRK4 A142V, GRK4 A486V), $11{\beta}$-hydroxysteroid dehydrogenase type-2 (HSD $11{\beta}$-2), neural precursor cell-expressed developmentally down regulated 4 like (NEDD4L),and solute carrier family 12(sodium/chloride transporters)-member 3 (SLC 12A3). We found that polymorphisms of salt-sensitive genes such as ACE, $CYP11{\beta}$-2, GRK4, SLC12A3, and GNB3 may be positively associated with human obesity. Conclusion: Despite gender, ethnic, and age differences in genetics studies, hypertensive obese children and adults who are carriers of specific salt-sensitive genes are recommended to reduce their sodium intake. We believe that our findings can contribute to the prevention of early-onset of chronic diseases in obese children by facilitating personalized diet-management of obesity from childhood to adulthood.

• 한국항공우주학회지
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• 제49권5호
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• pp.355-363
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• 2021

리오셀계 탄소/페놀릭 복합재료의 항공우주용 내열 부품 적용 가능성을 확인하기 위하여 내열성능 평가 및 열 해석을 수행하였다. 탄소/페놀릭의 열반응 평가는 내열성능평가모터(Thermal Protection Evaluation Motor, TPEM)로 수행되었다. 본 논문에서는 열 해석을 위해 유체의 경계층 해석을 고려한 경계층 적분 코드와 삭마 및 열분해를 고려한 MSC-Marc 2018 코드를 사용하였다. 추진기관의 압력 곡선, 연소 시험 후 절개된 목삽입재 시편을 통하여 삭마 및 단열성능을 분석하였고, 리오셀계 탄소/페놀릭 복합재료의 열반응은 레이온계 탄소/페놀릭 재료와 유사하였다. 연소시험을 통한 결과를 바탕으로 국산 리오셀계 탄소/페놀릭의 항공우주용 내열 부품으로의 적용 가능성을 확인하였다.

• The Plant Pathology Journal
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• 제39권1호
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• pp.1-20
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• 2023

In the past, rice bakanae was considered an endemic disease that did not cause significant losses in Korea; however, the disease has recently become a serious threat due to climate change, changes in farming practices, and the emergence of fungicide-resistant strains. Since the bakanae outbreak in 2006, its incidence has gradually decreased due to the application of effective control measures such as hot water immersion methods and seed disinfectants. However, in 2013, a marked increase in bakanae incidence was observed, causing problems for rice farmers. Therefore, in this review, we present the potential risks from climate change based on an epidemiological understanding of the pathogen, host plant, and environment, which are the key elements influencing the incidence of bakanae. In addition, disease management options to reduce the disease pressure of bakanae below the economic threshold level are investigated, with a specific focus on resistant varieties, as well as chemical, biological, cultural, and physical control methods. Lastly, as more effective countermeasures to bakanae, we propose an integrated disease management option that combines different control methods, including advanced imaging technologies such as remote sensing. In this review, we revisit and examine bakanae, a traditional seed-borne fungal disease that has not gained considerable attention in the agricultural history of Korea. Based on the understanding of the present significance and anticipated risks of the disease, the findings of this study are expected to provide useful information for the establishment of an effective response strategy to bakanae in the era of climate change.

• Pediatric Infection and Vaccine
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• 제22권3호
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• pp.178-185
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• 2015

목적: 국내 소아 그람음성균혈증에서 항생제 내성변화 및 항생제 사용량과의 관계를 분석하였다. 방법: 최근 10년간 18세 이하 입원 환자의 혈액에서 분리된 그람음성균의 항생제 내성률 변화 및 항생제 사용량과의 관계를 분석하였다. 결과: 폐렴막대균, 대장균, 녹농균, 아시네토박터 바우마니의 분리율은 연간 혈액배양 1,000건당 각각 4.6례, 3.5례, 3.4례 및 2.2례였다. 폐렴막대균에서 광범위 세팔로스포린에 대한 내성변화는 없었으나 2010년부터 카바페넴 내성 폐렴막대균이 동정된 후 점차 빈도가 증가하였다. 대장균의 광범위 세팔로스포린 내성이 10%에서 50%로 아시네토박터 바우마니의 카바페넴 내성이 11%에서 71%로 크게 증가하였다(P for trend <0.01). 녹농균은 여러 항생제에 높은 내성을 보였으나 유의한 내성변화를 보이지 않았다. 대장균의 cefepime 내성과 cefepime 사용량 사이에 유의한 양의 상관관계를 보였다(r=0.900, P=0.037). 결론: 국내 소아에서 발생한 그람음성균 균혈증 분석시 카바페넴 및 광범위 세팔로스포린 내성이 증가하였고 일부에서 항생제 사용량과의 관련성을 확인하였다. 이는 원내 경험적 항생제 결정시 중요한 고려 사항이며 추후에도 지속적인 원내 항생제 사용량 및 내성률에 대한 감시가 필요하겠다.

• 한국방재학회 논문집
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• 제10권5호
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• pp.9-15
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• 2010

최근 사용이 늘어나고 있는 고강도 콘크리트는 화재에 취약하여 고열에 의해 내부 수증기압의 상승으로 폭렬 현상이 발생하게 된다. 이러한 폭렬 현상의 방지 방안으로 유기질 섬유를 이용한 방법이 가장 많이 연구되고 있지만 이 방법은 결국 화재 후 콘크리트의 강도 저하를 초래하게 된다. 따라서 본 연구는 포비성 Alkali-Silicates계 내화재를 피복하여 유기질 섬유를 적용한 경우와 폭렬 특성 및 잔존 압축강도 특성을 검토하였다. 유기질 섬유의 혼입 방법으로 P.P, Nylon 섬유를 사용하였고, 내화 피복의 방법으로 포비성 Alkali-Silciates계 내화재를 사용하였다. 내화 시험은 자체 제작한 가열로에서 화염방사기를 이용하여 3시간 동안 화염 실험을 실시하였다. P.P 섬유를 혼입한 경우 폭렬은 방지 하였지만 잔존 압축강도는 측정할 수 없었고, 포비성 Alkali-Silicates계 내화재로 피복한 경우 폭렬 방지뿐만 아니라 잔존 압축강도가 최고 96%까지 유지되었다.