• 한국전기전자재료학회논문지
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• 제36권3호
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• pp.249-254
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• 2023

La_0.7-xCe_xSr_0.3MnO₃ specimens were fabricated by a solid state reaction method and structural and electrical properties with variation of Ce⁴⁺ contents were measured. All specimens exhibited a polycrystalline rhombohedral crystal structure, and the (110) peaks were shifted to low angle side with increasing the amount of Ce⁴⁺ contents. As Ce⁴⁺ ions with different ion radii and charges are substituted with La³⁺ ions, electrical properties are thought to be affected by changes in the double exchange interaction between Mn³⁺-Mn⁴⁺ ions due to distortion of the unit lattice, a decrease in oxygen vacancy concentration, and an increase in lattice defects. Resistivity gradually decrease as the amount of Ce⁴⁺ added increased, and negative temperature coefficient of resistance (NTCR) properties were shown in all specimens. In the La_0.5Ce_0.2Sr_0.3MnO₃ specimens, electrical resistivity, TCR and B-value were 31.8 Ω-cm, 0.55%/℃ and 605 K, respectively.

• 한국식생활문화학회지
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• 제25권5호
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• pp.544-557
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• 2010

This study was performed with Korean adults to investigate Makgeolli drinking behavior, preference, and perception about Makgeolli and health, as well as Makgeolli complaints and prices. A survey questionnaire was formulated to obtain information on demographic variables, drinking habits, and perceptions about Makgeolli's function, price, and complaints. The questionnaire was distributed to 468 adults living in the capital area. The results are as follows. Makgeolli (16.1%) was third preferred, following Soju (45.1%) and beer (30.7%), and no significant differences were observed by gender and income, but the preference for Makgeolli increased with increasing age (p<0.001). According to the survey, the largest reason both genders drank Makgeolli was that it tastes good. Men preferred Makgeolli for its health effects and cheap price, while women preferred it for the atmosphere while drinking it. Also, older people and those with higher incomes preferred drinking Makgeolli for its health effect rather than its good taste (p<0.001 for each). No significant difference was observed by gender for the question "Do you think that Makgeolli has a health-promoting effect?" Overall, 51% of the subjects gave positive answers and only 5.9% gave negative answers. Significantly, older people and those with a higher income had a higher rate of answering positively to this question. Belching (45.1%) and headache (29.9%) were the most common symptoms among the side effects of drinking Makgeolli. No significant difference was observed by gender or income, but older people had a higher rate of belching and fewer headaches than younger people (p<0.001). Women had a significantly higher rate of perceiving that Makgeolli was cheap than men. Age and income differences did not influence price perception. To the question "What is the ideal price for high quality Makgeolli", 32.1% answered that the present rate (1,000 won) was ideal, and 59.4% answered that a price between 1,000 and 2,000 won was ideal. These results indicate that the high preference for Makgeolli is due to its good taste and health effects. However, belching and headache caused by drinking Makgeolli were the most common complaints and, thus, must be solved. Some opinions indicated that Makgeolli must eliminate its low-quality image, but, according to this survey, most subjects answered that the ideal price of higher-quality Makgeolli should be increased slightly, which would cause price resistance.

• Pediatric Infection and Vaccine
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• 제30권1호
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• pp.47-54
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• 2023

최근 광범위 항생제 사용의 증가로 인한 다제내성 그람 음성균의 출현이 전 세계적으로 문제가 되고 있다. 특히 다제내성 녹농균(multidrug-resistant Pseudomonas aeruginosa) 감염의 치료는 어려우며 중환자의 사망률을 증가시키는 원인이 된다. 세프톨로잔-타조박탐(ceftolozane-tazobactam, Zerbaxa^TM)은 5세대 세팔로스포린과 베타락탐 분해효소저해제로 다제내성 녹농균에 의한 복잡성 요로감염과 복잡성 복강내 감염의 치료에 효과가 있는 것으로 입증되었다. 본지에서 저자들은 소아청소년 혈액암 환자에서 발생한 다제내성 녹농균에 의한 균혈증을 세프톨로잔-타조박탐을 사용하여 성공적으로 치료한 국내 첫 번째 사례를 보고하고자 한다.

• 대한토목학회논문집
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• 제26권4A호
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• pp.647-657
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• 2006

허용응력설계법과 극한한계 상태 설계법에 근거한 케이블과 보강형을 갖는 PSC 사장교의 예를 통해서 통계학적 확률분포를 고려한 확률론적인 위험성을 평가하였다. 사용성 한계상태 및 극한 한계상태에서의 케이블요소의 파괴확률과 거더의 최대 정모멘트. 부모멘트 발생단면, 그리고 최대전단력의 작용단면에서 각각의 요소 파괴 확률을 설계변수의 응답면에서 검토하였다. 응답면 기법(RSM)은 복잡한 다자유도 구조물에서 MCS를 사용하여 얻을 수 없는 상대적으로 매우 작은 파괴 확률값을 얻기 위해 사용이 가능할 뿐만 아니라, FOSM으로 쉽게 얻을 수 없는 한계상태방정식의 미분형태에도 성공적으로 적용이 가능 하다. 케이블과 보강형으로 구성된 병렬저항구조를 시스템 해석을 위해 각각 직렬구조로 연결하여 전체구조물의 체계신뢰성을 평가하고, 제안된 붕괴모드조합 예측값과 비교분석하였다. 제안된 붕괴모드의 조합에 의한 파괴확률검토는 조건부 파괴에 대한 동일한 발생확률을 구하며, 순열방법보다 개선된 시간비용과 효율성을 제공하며, 상하한계파괴확률을 구하는 체계 신뢰성해석에서 검토되지 않는 요소파괴의 조합에 의한 시스템의 위험성 검토를 제공한다.

• 한국작물학회:학술대회논문집
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• 한국작물학회 2022년도 추계학술대회
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• pp.57-57
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• 2022

In many areas of the world, salt damage and drought have had a negative impact on human survival due to a decrease in agricultural productivity. For instance, about 50% of agricultural land will be affected by salt damage by 2050. Biostimulants such as plant extracts can not only increase the nutrient utilization efficiency of plants, but also promote plant growth and increase resistance to abiotic or biotic stress. Therefore, the objective of this study was to determine how selected plant extracts might reduce levels of stress caused by drought and salt and to better understand the physiological response mechanisms of rice plants. In this study, we used Soybean leaves, Soybean stems and Allium tuberosum, Allium cepa, Hizikia fusiforme, and Gracilaria verrucosa extracts were used. These extracts had been used in previous studies and were found to be effective. The materials were dried in a dry oven at 50℃ for 5 days and ground using a blender. Each 50 g of materials was put in 1 L of distilled water, stirred for 24 hours, filtered using 4 layers of mirocloth, and then concentrated using a concentrator. Rice (cv. Hopumbyeo) seeds were immersed and germinated, and then sown in seedbeds filled with commercial soil. In drought experiments, three rice seedlings at 1 week after seeding was transplanted into 100 ml cups filled with commercial soils and grown until the 4-leaf stage. For this experiment, the soil weight in a cup was equalized, and water was allowed to become 100% saturated and then drained for 24 hours. Thereafter, plant extracts at 3% concentrations were applied to the soils. For NaCl treatments, rice plants at 17 days after seeding were treated with either 100 mM NaCl or plant extracts at 1%+ 100 mM NaCl combinations in the growth chamber. Leaf injury, relative water content, photosynthetic efficiency, and chlorophyll contents were measured at 3, 5, and 6 days after treatments. Shoot fresh weight of rice under drought conditions increased 28-37% in response to treatments of Soybean leaf, Soybean stem, Allium tuberosum, Allium cepa, Hizikia fusiforme, and Gracilaria verrucosa extracts at 3% when compared with control plants. Shoot fresh weight of rice subjected to 100 mM NaCl treatments also increased by 6-24% in response to Soybean leaf, Soybean stem, Allium tuberosum, Allium cepa, Hizikia fusiforme, and Gracilaria verrucosa extracts at 3% when compared with control plants. Compared to the control, rice plants treated with these six extracts and subjected to drought conditions had significantly higher relative water content, Fv/Fm, total chlorophyll and total carotenoids than control plants. With the exception of relative water contents, rice plants treated with the six extracts and subjected to salt stress (100 mM NaCl treatments) had significantly higher Fv/Fm, total chlorophyll and total carotenoids than control plants. However, the type of extract used did not produce significant difference in these parameters. Thus, all the plant extracts used in this study could mitigate drought and NaCl stresses and could also contribute substantially to sustainable crop production.

• Steel and Composite Structures
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• 제49권2호
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• pp.245-255
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• 2023

The present paper summarizes the results of an experimental program on the influence of using waste lathe scraps in the concrete mixture on the shear behavior of RC beams with different amounts of shear reinforcement. Three different volumetric ratios (1, 2 and %3) for the scraps and three different stirrup spacings (160, 200 and 270 mm) were adopted in the tests. The shear span-to-depth ratios of the beams were 2.67 and the stirrup spacing exceeded the maximum spacing limit in the building codes to unfold the contribution of lathe scraps to the shear resistances of shear-deficient beams, subject to shear-dominated failure (shear-tension). The experiments depicted that the lathe scraps have a pronounced contribution to the shear strength and load-deflection behavior of RC beams with widely-spaced stirrups. Namely, with the addition of 1%, 2% and 3% waste lathe scraps, the load-bearing capacity escalated by 9.1%, 21.8% and 32.8%, respectively, compared to the reference beam. On the other hand, the contribution of the lathe scraps to the load capacity decreases with decreasing stirrup spacing, since the closely-spaced stirrups bear the shear stresses and render the contribution of the scraps to shear resistance insignificant. The load capacity, deformation ductility index (DDI) and modulus of toughness (MOT) values of the beams were shown to increase with the volumetric fraction of scraps if the stirrups are spaced at about two times the beam depth. For the specimens with a stirrup spacing of about the beam depth, the scraps were found to have no considerable contribution to the load capacity and the deformation capacity beyond the ultimate load. In other words, for lathe scrap contents of 1-3%, the DDI values increased by 5-23% and the MOT values by 63.5-165% with respect to the reference beam with a stirrup spacing of 270 mm. The influence of the lathe scraps to the DDI and MOT values were rather limited and even sometimes negative for the stirrup spacing values of 160 and 200 mm.

• Journal of Animal Science and Technology
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• 제65권5호
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• pp.1040-1052
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• 2023

The objective of this study was to investigate the protective effects of functional nutrients including various functional amino acids, vitamins, and minerals on chicken intestinal epithelial cells (cIECs) treated with oxidative stress. The cIECs were isolated from specific pathogen free eggs. Cells were exposed to 0 mM supplement (control), 20 mM threonine (Thr), 0.4 mM tryptophan (Trp), 1 mM glycine (Gly), 10 μM vitamin C (VC), 40 μM vitamin E (VE), 5 μM vitamin A (VA), 34 μM chromium (Cr), 0.42 μM selenium (Se), and 50 μM zinc (Zn) for 24 h with 6 replicates for each treatment. After 24 h, cells were further incubated with fresh culture medium (positive control, PC) or 1 mM H₂O₂ with different supplements (negative control, NC and each treatment). Oxidative stress was measured by cell proliferation, whereas tight junction barrier function was analyzed by fluorescein isothiocyanate (FITC)-dextran permeability and transepithelial electrical resistance (TEER). Results indicated that cell viability and TEER values were less (p < 0.05) in NC treatments with oxidative stress than in PC treatments. In addition, FITC-dextran values were greater (p < 0.05) in NC treatments with oxidative stress than in PC treatments. The supplementations of Thr, Trp, Gly, VC, and VE in cells treated with H₂O₂ showed greater (p < 0.05) cell viability than the supplementation of VA, Cr, Se, and Zn. The supplementations of Trp, Gly, VC, and Se in cells treated with H₂O₂ showed the least (p < 0.05) cellular permeability. In addition, the supplementation of Thr, VE, VA, Cr, and Zn in cells treated with H₂O₂ decreased (p < 0.05) cellular permeability. At 48 h, the supplementations of Thr, Trp, and Gly in cells treated with H₂O₂ showed the greatest (p < 0.05) TEER values among all treatments, and the supplementations of VC and VE in cells treated with H₂O₂ showed greater (p < 0.05) TEER values than the supplementations of VA, Cr, Se, and Zn in cells treated with H₂O₂. In conclusion, Thr, Trp, Gly, and VC supplements were effective in improving cell viability and intestinal barrier function of cIECs exposed to oxidative stress.

• Safety and Health at Work
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• 제14권4호
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• pp.457-466
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• 2023

Background: During hot environment work tasks with whole-body enclosed anti-bioaerosol suit, the combined effect of heavy sweating and exhaled hot humid air may cause the N95 medical respirator to saturate with water/sweat (i.e., water-blocking). Methods: 32 young male subjects with different body mass indexes (BMI) in whole-body protection (N95 medical respirator + one-piece protective suit + head covering + protective face screen + gloves + shoe covers) were asked to simulate waste collecting from each isolated room in a seven-story building at 27-28℃, and the weight, inhalation resistance (R_f), and aerosol penetration of the respirator before worn and after water-blocking were analyzed. Results: All subjects reported water-blocking asphyxia of the N95 respirators within 36-67 min of the task. When water-blocking occurred, the R_f and 10-200 nm total aerosol penetration (P_t) of the respirators reached up to 1270-1810 Pa and 17.3-23.3%, respectively, which were 10 and 8 times of that before wearing. The most penetration particle size of the respirators increased from 49-65 nm before worn to 115-154 nm under water-blocking condition, and the corresponding maximum size-dependent aerosol penetration increased from 2.5-3.5% to 20-27%. With the increase of BMI, the water-blocking occurrence time firstly increased then reduced, while the R_f, P_t, and absorbed water all increased significantly. Conclusions: This study reveals respirator water-blocking and its serious negative impacts on respiratory protection. When performing moderate-to-high-load tasks with whole-body protection in a hot environment, it is recommended that respirator be replaced with a new one at least every hour to avoid water-blocking asphyxia.

• 한국유기농업학회지
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• 제32권2호
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• pp.233-245
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• 2024

고추재배지에 6월 7일부터 8월 26일까지 총 7회 항생제가 처리된 토양중 항생제의 잔류량을 조사한 결과, 조사대상 3종의 항생제(아목시실린, 옥시테트라사이클린 및 클로르테트라사이클린) 모두 background level에서 검출되지 않았으나, background 농도의 10배 농도 처리구와 50배 농도 처리구에서는 2-10 ㎍/kg 이상 수준으로 검출되었다. 자연함유량 수준의 50배 농도 수준으로 고농도로 처리된 경우에도 고추잎(줄기)과 고추 과실에서 모두 검출한계 미만으로 나타났고, 고추뿌리에서만 미량으로 검출되어 농작물의 안전성이 확보된 것으로 판단되지만 다양한 환경에서 다양한 항생제를 대상으로 작물체로의 흡수이행 및 토양환경중 잔류에 대한 장기적인 환경영향평가가 필요할 것으로 판단된다. Background level의 농도 처리구에서는 TF 값이 0으로 나타났으나, backgroud level의 10배 농도 처리구에서 TF 값은 아목시실린 0.45, 옥시테트라사이클린 0.17 클로로테트라사이클린 0.18 이하로 나타났고, background level의 50배 농도 처리구에서 TF 값은 아목시실린 0.52, 옥시테트라사이클린 0.16, 테트라사이클린 0.15 이하로 나타났다. 단기간에 축산용 항생제가 비의도적으로 농경지 토양에 유입될 경우 농경지 토양환경과 농작물 안전성은 우려할 만한 수준은 아니지만, 장기적이고 지속적으로 축산용 항생제가 농경지 토양에 유입될 경우에는 바람직하지 못한 영향을 끼칠 수 있으므로 모니터링과 환경영향평가가 수행되어야 할 것이다.

• Tuberculosis and Respiratory Diseases
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• 제39권5호
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• pp.425-432
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• 1992

저자들은 1982년 1월부터 1991년 12월까지 결핵연구원 부설의원에 내원하여 MOTT균에 의한 폐질환으로 진단받고 임상적으로 의미있게 검출된 29예와, 12개월 이상까지 관찰할 수 있었던 19예의 환자즐 대상으로 조사하여 본 결과 다음과 같은 결론을 얻었다. 1) 원인균은 M. avium-intracellulare이 19예로 66%, M. fortuitum이 5예로 17%, M. chelonei가 4예로 14% 그리고 M. szulgai가 1예로 3%였다. 2) 성별 분포는 남녀의 비가 1.9 : 1로 남자에서 많았다. 3) 환자의 연령 분포는 51~60세가 많았다. 4) 흉부엑스선 사진상 병변의 크기는 대상 29예중 29예 모두가 중등증 이상의 병변을 가지고 있었으며, 병변은 양쪽폐의 상부 특히 우측에서 더 많았다. 5) 초진시 임상증상은 기침, 객담 그 다음으로 호흡곤란 순서로 나타났다. 6) 대상 29예 모두다 과거에 폐결핵을 앓은 병력이 있었다. 7) 약제감수성검사 결과 CS, KM 그리고 EVM 약제에 48~52%가 감수성을 나타내었다. 8) 1년이상 경과관찰이 가능했던 19예에 대해서 균음전에 성공한 경우는 3예였으며 M. fortuitum 2예와 M. szulgai 1예였다. M. fortuitum 2예중 1예는 폐절제술을 시행하였던 경우였고, 나머지 1예는 화학요법만으로 균음전에 성공하였으나 무의한 군서였을 가능성을 배제할 수 없다. M. szulgai 1예는 치료시작 2개월 이내에 균음전이 되고 흉부 엑스선사진 결과 현저하게 호전되어 1년후에 치유 판정을 하였다. 내원 당시와 경과관찰중의 마지막 흉부엑스선 사진을 비교하였을때 균음전에 실패한 16중 8예(50%)는 변화가 없었고, 4예(25%)는 경하게 호전, 나머지 4예(25%)에서는 경하게 악화되는 소견을 보여주었다. 전반적으로, 균이 계속 검출된다 하여도 변화가 없거나 호전되는 소견을 보이고 있었으며, 일부가 악화되는 소견을 보이고 있으나 그정도도 경하였다.