• Nuclear Engineering and Technology
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• 제50권5호
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• pp.724-730
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• 2018

Chromium and chromium nitride were selected as potential barriers to prevent fuel-clad chemical interaction (FCCI) between the cladding and the fuel material. In this study, ferritic/martensitic HT-9 steel and misch metal were used to simulate the reaction between the cladding and fuel fission product, respectively. Radio frequency magnetron sputtering was used to deposit Cr and CrN films onto the cladding, and the gas flow rates of argon and nitrogen were fixed at certain values for each sample to control the deposition rate and the crystal structure of the films. The samples were heated for 24 h at 933 K through the diffusion couple test, and considerable amount of interdiffusion (max. thickness: $550{\mu}m$) occurred at the interface between HT-9 and misch metal when the argon and nitrogen were used individually. The elemental contents of misch metal were detected at the HT-9 through energy dispersive X-ray spectroscopy due to the interdiffusion. However, the specimens that were sputtered by mixed gases (Ar and $N_2$) exhibited excellent resistance to FCCI. The thickness of these CrN films were only $4{\mu}m$, but these films effectively prevented the FCCI due to their high adhesion strength (frictional force ${\geq}1,200{\mu}m$) and dense columnar microstructures.

• 한국식품영양학회지
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• 제31권6호
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• pp.890-896
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• 2018

The aim of this study was to determine volatile flavor compounds in Shingo pear juice. Volatile flavor compounds were analyzed using solid-phase micro-extraction (SPME) - gas chromatography-mass spectrometry (GC-MS). The effect of inorganic salts solution on the extraction ability of the SPME fiber was treated by adding saturated $CaCl_2$ solution at the ratio of 1:20 (v/v) after 0, 60, 120 min of preparing pear juice, respectively. As a result, a total of 22 volatile compounds were identified in Shingo pear juice. Ethyl acetate was found to be the most abundant volatile compound ($13.36{\sim}19.61{\mu}g/kg$), followed in order by hexanal, ethyl hexanoate, ethyl 3-(methylthio)-2-propenoate, ethyl octanoate and 2-hexenal. Total contents of volatile flavor compounds were $31.07{\mu}g/kg$ (control), $40.93{\mu}g/kg$ (0 min), $27.62{\mu}g/kg$ (60 min) and $26.32{\mu}g/kg$ (120 min). This result indicated that the addition of saline solutions could inhibit the enzymatic reaction of volatile flavor compounds effectively when treated as soon as juice preparation.

• Corrosion Science and Technology
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• 제21권1호
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• pp.32-40
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• 2022

The o-Vanillin - Glutamine Schiff base [2-Hydroxy-3-Methoxy BenzylidineCarbomyl) -2-Butanoic Acid] was examined for low carbon steel corrosion inhibition in acid media. Weight loss studies were carried out at three different temperatures to determine the inhibition efficiency (IE). Electrochemical impedance spectroscopy revealed that the charge transfer resistance controlled the corrosion reaction and Tafel polarization indicated that the Schiff base acts as mixed mode of inhibitor. SEM images were recorded for the surface morphology of the low carbon steel surface. DFT studies revealed corrosion control mechanisms using quantum chemical parameters such as E_HOMO, E_LUMO, energy gap (∆E), chemical Hardness (η), chemical Softness (σ), Electronegativity (χ), and the fraction of electron transferred (∆N), which is calculated using Gaussian software 09. The gas-phase geometry was fully optimized in the Density Functional Theory (DFT/B3LYP-6-31G (d)).The DFT results are in good agreement with the experimental results. All the results proved that the Schiff Base (2-Hydroxy-3-Metoxy BenzylidineCarbomyl) -2-Butanoic is a suitable alternative for corrosion inhibition of low carbon steel in acid media.

• 한국토양비료학회지
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• 제49권1호
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• pp.30-35
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• 2016

Rice cultivation in paddy field affects the global balance of methane ($CH_4$) as a key greenhouse gas. To evaluate a potential use of by-product gypsum fertilizer (BGF) in reducing $CH_4$ emission from paddy soil, $CH_4$ fluxes from a paddy soil applied with BGF different levels (0, 2, 4 and $8Mg\;ha^{-1}$) were investigated by closed-chamber method during rice cultivation period. $CH_4$ flux significantly decreased (p<0.05) with increasing level of BGF application. $8Mg\;ha^{-1}$ of BGF addition in soil reduced $CH_4$ flux by 60.6% compared to control. Decreased soil redox potential (Eh) resulted in increasing $CH_4$ emission through a $CO_2$ reduction reaction. The concentrations of dissolved calcium (Ca) and sulfate ion (${SO_4}^{2-}$) in soil pore water were significantly increased as the application rate of BGF increased and showed negatively correlations with $CH_4$ flux. Decreased $CH_4$ flux with BGF application implied that ${SO_4}^{2-}$ ion led to decreases in electron availability for methanogen and precipitation reaction of Ca ion with inorganic carbon including carbonate and bicarbonate as a source of $CH_4$ formation under anoxic condition. BGF application also increased rice grain yield by 16% at $8Mg\;ha^{-1}$ of BGF addition. Therefore, our results suggest that BGF application can be a good soil management practice to reduce $CH_4$ emission from paddy soil and to increase rice yield.

• 한국산학기술학회논문지
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• 제19권4호
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• pp.132-137
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• 2018

2015년 화학물질관리법 시행 이후 화학 사고 발생 수는 감소 추세에 있으나, 최근 인쇄회로기판(PCB) 제조시설에서 유사한 유형의 사고가 반복적으로 발생함에 따라 실험을 통해 사고 원인을 조사 분석하였다. 해당 사고는 인쇄회로기판 제조공정 내 에칭용액으로 사용한 유해화학물질인 염산과 과산화수소가 월류하여 발생한 사고로 작업자 부주의와 시설 관리 미흡이 주된 사고 원인으로 조사되었다. 사고 원인을 규명하기 위해 실시한 $Cl^-$의 함량 분석 결과 과산화수소 시료에서 66.85 ppm로 측정되어 사고 물질인 염산과 과산화수소의 혼합경로를 확인할 수 있었으며, 반응실험을 통해 반응열이 $50.5^{\circ}C$까지 발생함에 따라 PVC 저장탱크의 변형과 유독가스인 염소가스 발생을 확인하였다. 본 연구를 통해 인쇄회로기판 제조시설의 에칭공정에서의 과충전, 역류방지, 누출감지장치와 혼합방지를 위한 저장탱크 분리 설계 등 시설 안전 관리 방안과 해당 장치의 장외영향평가 검토 필요성을 제시하고자 하였다. 또한 동일 유형의 사고 재발 방지를 위하여 주기적인 시설 안전점검과 작업자의 안전교육 강화의 필요성에 대하여 논의하였다.

• 대한환경공학회지
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• 제32권10호
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• pp.957-964
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• 2010

경유차 배출가스에 의해 활성이 크게 저하된, 촉매가 담지된 자연 재생식 매연 저감장치인 DPF를 대상으로 여러 가지 조건에서 재제조를 수행한 후 재제조된 DPF의 일산화탄소(CO)와 총 탄화수소(THC) 그리고 입자상 물질(PM)의 저감효율과 DPF 표면 물성 특성을 분석하여 사용후 DPF에 대한 재제조 효과를 관찰하였다. 재제조된 DPF에 대한 오염물질 저감성능 평가는 제작된 디젤 엔진 다이나모 장치를 이용, 배기가스를 일부 우회시켜 온도와 공간속도 조절이 가능한 촉매 반응장치로 수행 하였으며, DPF 표면 물성 분석은 광학현미경, EDX, ICP, TGA 그리고 porosimeter를 이용 하였다. 연구 수행 결과 사용 후 DPF를 본 연구에서 적용된 고온 배소 세정, 산성/염기성 용액에 의한 초음파 세정, 세정 후 촉매 활성성분 재 함침에 의한 재제조를 수행할 경우, 재제조된 DPF의 성능이 신품 성능대비 95% 이상으로 회복되는 것을 확인 하였으며, 광학현미경, EDX, TGA와 ICP등의 분석을 통해 본 연구 조건에서의 재제조 과정으로, DPF의 활성저하 원인이 되었던 각종 불순성분 대부분이 사용후 DPF 표면으로 부터 제거되는 것을 확인 하였다.

• Tuberculosis and Respiratory Diseases
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• 제59권4호
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• pp.397-405
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• 2005

배 경 : Laminin은 생체조직의 세포외기질에 함유되어 있는 당단백질로 특히 기저막내에 특이적으로 분포되어 있다. 저자들은 군중집회 해산용으로 혹은 군사용으로 널리 사용되고 있는 CS 가스(ortho-chlorobenzylidine malononitrile)가 폭로되었을 때 흰쥐의 폐조직내 laminin에 미치는 영향을 밝히고자 하였다. 대상 및 방법 : 본 실험에 사용한 실험동물은 청정동물실에서 사육한 생후 21일령의 흰쥐 (Sprague-Dawley계) 35마리를 사용하였다. 실험동물은 대조군에 5마리, 실험군에 30마리를 배정하였다. CS 가스에 폭로 후 흰쥐를 12시간, 1일, 2일, 3일, 5일 및 7일 경과후 희생시켜 폐장을 절취하여 면역조직염색 및 면역도금법을 시행하였다. 결 과 : 상기와 같이 조직면역반응과 염색을 시행한 후 조직을 관찰하여 다음과 같은 결과를 얻었다. CS 가스 투여후 2일 경과군의 흰쥐 폐포막에는 림파구, 단핵구등이 침투되기 시작하여 3일 경과군에서는 강도의 염증조직이 관찰되었다. 대조군과 CS 가스 투여 12시간군의 폐장의 제2형폐포세포내에 금과립은 층상체주위와 외형질에서 소수 관찰되었다. 결 론 : 이상과 같은 결과로 흰쥐에 CS 가스를 계속 3일간 투여했을 경우 폐포에서 염증조 직이 형성되고 이때 기저막내 laminin의 분포는 일시 감소되나 염증조직의 소멸과 함께 다시 증가되는 것을 보아 laminin이 조직재형성에의 역할이 흰쥐 폐포에서도 일어나고 있음을 알 수 있었고, 면역금과립방법을 이용한 전자현미경 검사에서 제2형폐포세포내 laminin의 분포도 증명할 수 있었다.

• Maxillofacial Plastic and Reconstructive Surgery
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• 제11권1호
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• pp.153-170
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• 1989

Recently, frequently using hyperbaric oxygen therapy is known for its effectiveness on the healing of problem wounds such as osteomyelitis, osteoradionecrosis and gas gangrenous wound etc. The main objectives of this study was to determine the best protocol of its application of hyperbaric oxygen therapy. Author used 238 rats (Sprague-Dawley strain) deviding into 2 Groups, experimental I group for skin and experimental II group for palatal mucosal ischemic wounds, and observed its effects by microscopically. The obtained results summarized as follows; 1. Severe infiltration of inflammatory cells was observed in initial stages of both control and experimental I group. The infiltration showed decreasing tendency at 5th day of experimental D, E, F group while at 8th day in control group In d, f of experimental II group showed decreasing tendency at 8th experimental day while at 12th day in control group. 2. Macrophages appeared at 2nd day in D of experimental I group while at 6th day in control group. In d, f of experimental II group appeared at 6th day while at 10th day in control group. 3. As to the proliferation of capillary blood vessels showed at 3-4 day in most of experimental I group severely while at 8th day in control group. In experimental II group, it was at 8th day and 12th day respectively. 4. The proliferation of fibroblasts showed rather rapider in experimental I group, at 4-6th day, while at 8th day in control group. In experimental II group, it was at 8th day and 12th day respectively. 5. As to the collagen formations, it was at 4th day in experimental I group while at 8th day in control group. In experimental II group, it was at 6th day and 10th day respectively. 6. 5 rats (2.0 %) in E group and 8 rats (3.4 %) in f group showed oxygen toxic reaction, such as unstable attitude and tremor, during the experiments. This hyperbaric oxygen animal experiments disclosed excellent effects on the ischemic wound healing and it is thought to be the best protocol of its application was on D group (2.5 ATM. and 2 hrs, exposure).

• 한국응용과학기술학회지
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• 제33권1호
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• pp.23-29
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• 2016

육방정계 우르자이츠형의 산화아연은 n형 반도체로써 3.37 eV의 넓은 밴드갭 에너지와 60 meV의 큰 엑시톤 바인딩 에너지를 가진 물질이다. 가스센서, 발광 다이오드, 염료 감응 태양 전지, 염료오염의 분해 등의 넓은 범위에서 활용이 가능하다. 합성 시 마이크로파 수열합성법을 사용하게 되면 높은 수율, 빠른 반응속도, 에너지 절약의 장점이 있다. 아민첨가제는 수산이온 생성 및 킬레이트 효과로 인해 산화아연 입자 형상을 조정하는 역할을 한다. 본 논문에서는 전구체로는 질산아연육수화물을 사용하였고, 형상조정제로는 에탄올아민, 에틸렌디아민, 디에틸렌트리아민, 헥사메틸렌테트라민을 사용하였다. 수산화소듐을 사용하여 용액을 pH 11로 조정하였다. 합성된 산화아연은 별모양, 막대형, 꽃모양, 원추형의 다양한 형상을 확인할 수 있었다. 아민첨가제에 의한 물리 화학적 특성과 광학적 특성을 분석하기 위해 XRD, SEM, EDS, FT-IR, UV-vis 스펙트럼, PL 스펙트럼을 사용하였다.

• The Plant Pathology Journal
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• 제39권1호
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• pp.88-107
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• 2023

In the present investigation, bacterial isolates from infected apple trees causing apple canker during winter were studied in the northern Gyeongbuk Province, Korea. The pathogen was identified as Pseudomonas syringae pv. syringae (Pss) through various physiological and biochemical characterization assays such as BIOLOG, gas chromatography of fatty acid methyl esters, and 16S rRNA. Bioassays for the production of phytotoxins were positive for syringopeptin and syringomycin against Bacillus megaterium and Geotrichum candidum, respectively. The polymerase chain reaction (PCR) method enabled the detection of toxin-producing genes, syrB1, and sypB in Pss. The differentiation of strains was performed using LOPAT and GATTa tests. Pss further exhibited ice nucleation activity (INA) at a temperature of -0.7℃, indicating an INA⁺ bacterium. The ice-nucleating temperature was -4.7℃ for a non-treated control (sterilized distilled water), whereas it was -9.6℃ for an INA^- bacterium Escherichia coli TOP10. These methods detected pathogenic strains from apple orchards. Pss might exist in an apple tree during ice injury, and it secretes a toxin that makes leaves yellow and cause canker symptoms. Until now, Korea has not developed antibiotics targeting Pss. Therefore, it is necessary to develop effective disease control to combat Pss in apple orchards. Pathogenicity test on apple leaves and stems showed canker symptoms. The pathogenic bacterium was re-isolated from symptomatic plant tissue and confirmed as original isolates by 16S rRNA. Repetitive element sequence-based PCR and enterobacterial repetitive intergenic consensus PCR primers revealed different genetic profiles within P. syringae pathovars. High antibiotic susceptibility results showed the misreading of mRNA caused by streptomycin and oxytetracycline.