• 한국주조공학회지
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• 제10권6호
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• pp.520-527
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• 1990

In order to reduce segregation in 12%Cr steel ingots of 60-100tons, numerical analysis by computer was applied to simulate solidification profiles and the profiles of liguid-solid coexisting zone in accordance with the ratios of H(Height) /D(diameter) of 100-ton ingot. The result is that the ratio of L(vertical length) /D(diameter) of liquid-solid coexisting zone was reduced in proportion to the decrease of H/D ratio. With the reduced H/D ratio(0.92) of ingot, the segregation in 60-ton ingot of 12% Cr steel can be much reduced and recovery was also improved by reducing ingot weight.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2000년도 봄 학술발표회 논문집
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• pp.205-210
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• 2000

This study concerns the cement-solidification. stabilization of the electric furnace dust. Compressive strength and leaching test of heavy metals were evaluated for varing types and ratios of cements and the effect of some additives of hauyne clinker and slag were also discussed. In this cases of using cement binders more than 30%, the compressive strength showed the values over 150kgf/cm2. so it can be used as filler for concrete precastings. Type III cement and Hauyne clinker improved the compressive strength, especially early strength. Leaching amount of heavy metals was decreased when using type III cement and adding hauyne clinker and slag. The values were especially low in the case of slag addition.

• Computers and Concrete
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• 제14권1호
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• pp.1-18
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• 2014

The addition of steel fibers in concrete mixture is recognized as a non-conventional mass reinforcement scheme that improves the torsional, flexural, and shear behavior of structural members. However, the analysis of fiber reinforced concrete beams under combined torsion, bending, and shear is limited because of the complicated nature of the problem. Therefore, nonlinear 3D finite element analysis was conducted using the "ANSYS CivilFEM" program to investigate the behavior of fiber reinforced concrete L-beams. These beams were tested at different reinforcement schemes and loading conditions. The reinforcement case parameters were set as follows: reinforced with longitudinal reinforcement only and reinforced with steel bars and stirrups. All beams were tested under two different combined loading conditions, namely, torsion-to-shear ratio (T/V) = 545 mm (high eccentricity) and T/V = 145 mm (low eccentricity). Eight intermediate L-beams were constructed and tested in a laboratory under combined torsion, bending, and shear to validate the finite element model. Comparisons with the experimental data reveal that the program can accurately predict the behavior of L-beams under different reinforcement cases and combined loading ratios. The ANSYS model accurately predicted the loads and deformations for various types of reinforcements in L-beams and captured the concrete strains of these beams.

• 한국식품과학회지
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• 제50권1호
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• pp.76-82
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• 2018

본 연구에서는 식물성 원료인 콩에 물의 비율을 달리하여 발효우유 베이스(base)를 제조하고, 식물성 젖산균인 김치 젖산균 L. plantarum와 식초 젖산균인 B. acidiproducens를 접종하여 제조한 발효우유의 물리 화학적 특성을 알아보고자 하였다. 콩과 물의 비율은 1:1인 것이 다른 비율보다 실험결과에서 이상적인 값을 보였다. L. plantarum 발효우유와 B. acidiproducens 발효우유는 pH와 산도, 생균수에서 대조군으로 사용한 YF 발효우유보다 낮은 값을 나타내었으나 발효우유 제조 규격에 적합한 수준이었다. L. plantarum 발효우유는 발효완료시점의 생균수에서 B. acidiproducens 발효우유보다 유의적으로 높은 값을 나타내었으나 (p<0.05) 완성된 발효우유의 향과 전체적 기호도에서 낮은 평가를 받았는데, 이는 발효우유의 신맛과 향으로 인한 결과로 사료된다. B. acidiproducens VG1 발효우유는 L. plantarum YD09 발효우유와 pH, 산도, 색도, 당도 및 점성에서 유사한 결과 값을 보였고, 생균수에서는 L. plantarum 발효우유보다 낮은 값을 나타내었지만, 관능검사에서 높은 선호도를 보였다. 결론적으로 김치 젖산균인 L. plantarum YD09과 식초에서 분리한 B. acidiproducens VG1은 시판되는 YF 균주보다 발효 초기 pH값이 높은 경향을 보였으나 발효가 완료된 시점에서 발효우유로써 규격에 합하는 결과 값을 나타낸 것으로 보아 발효우유 제조에 적합한 것으로 사료되며, 콩과 물의 비율을 1:1로 정하여 제조하는 것이 생균수가 높고, 커드 형성이 잘 되는 발효우유를 제조할 수 있을 것으로 보인다. 그리고 L. plantarum 보다 B. acidiproducens VG1을 사용하여 발효우유를 제조할 경우 신맛이 덜하고 시판되는 ABT-4 (YF)만큼 기호도가 높은 발효우유를 제조할 수 있을 것으로 사료된다.

• 대한기계학회논문집B
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• 제38권5호
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• pp.399-406
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• 2014

본 연구에서는 압력면윙렛/흡입면스퀼러형 터빈 동익 팁에 대하여 익렬 하류에서 3차원 유동 및 압력손실을 측정하였다. 팁간극비 h/s = 1.36%에 대하여, 흡입면스퀼러의 높이는 $h_s/s$ = 3.75%로 일정하게 유지하고, 압력면윙렛의 폭은 w/p = 2.64%, 5.28%, 7.92%, 10.55% 등으로 변화시키면서 실험을 수행하였다. 그 결과, 본 연구의 팁은 평면팁 대비 통로와류 영역에서 압력손실의 저감 효과가 매우 뛰어났지만, 팁누설와류 영역에서는 오히려 압력손실을 크게 증가시켰다. 본 연구의 질량평균 압력손실은 평면팁에 비해 크게 낮았지만, 전면스퀼러팁보다는 더 크게 나타났다. 압력면윙렛의 폭이 증가할수록 질량평균 압력손실은 감소하는 경향을 보였다.

• 한국식품과학회지
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• 제34권5호
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• pp.862-866
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• 2002

분말상태의 인삼속 식물들의 품종 및 원산지를 판별하기 위하여 SAW 센서가 내장된 PHGC를 이용하여 향기 패턴을 분석하였다. 한국 백삼을 1로 기준할 때 전체적인 Rt에 대한 frequency pattern의 면적비는 화기삼 $0.248{\sim}0.871$, 전칠삼 $0.030{\sim}0.674$, 중국산 백삼 $0.005{\sim}0.212$ 범위로 나타났다. 분명한 차이를 나타내는 몇 개의 특정 향기성분의 면적비를 보면 $Rt_{20.02}$에서 한국산 백삼 1일 때, 중국산 백삼 0.212, 화기삼 0.343, 전칠삼 0.065이었다. 또한 $Rt_{21.70}$과$Rt_{24.90}$에서 검출되는 향기성분의 면적비도 품종간의 차이가 뚜렷하였다. 한국산 백삼과 중국산 백삼에서 검출된 Rt_26.15 향기성분의 면적비는 각각 1과 0.185로 나타나 원산지간의 차이도 분명히 나타났다. $Rt_{26.15}$의 향기성분은 화기삼과 전칠삼에서는 검출되지 않았다. Frequency pattern, derivative pattern을 Vapor $print^{TM}$을 사용하여 도형화하여 비교한 결과 한국 백삼(Korean Panax ginseng C.A. Meyer), 화기삼(미국삼, 서양삼, Panax quinquefolium L.), 전칠삼(Panax notoginseng F.H. Chen), 중국산 백삼(Chinese Panax ginseng)은 서로 다른 패턴을 보여주어 품종간의 차이는 물론 원산지의 차이도 뚜렷하게 나타났다.

• Journal of the Korean Wood Science and Technology
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• 제47권4호
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• pp.393-407
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• 2019

본 연구에서는 Bacilluls subtilis가 함유된 목질계 인공토양(피트모스:펄라이트:폭쇄처리된 참나무:미생물제형=3:1:3:3, w/w/w/w)을 제조 하였으며, 이를 대조구토양과 0%, 25%, 50%, 75% 및 100% 비율로 혼합하여 참싸리 종자 파종 후 소규모 야외포트 현장적용 하였다. 현장적용에 따른 대조구토양, 혼합토양(대조구토양+인공토양) 및 인공토양의 물리 화학적 특성을 분석하였고 참싸리 줄기 및 뿌리생장을 비교하였다. 혼합토양에서는 $0.04g/cm^3$ 이하의 용적밀도, 85 % 이상의 공극률, pH 4.3 - 4.7, 0.5 dS/m 이하의 전기전도도, 15.0 - 26.5의 탄질비, 23.6% - 43.2%의 유기물 함량 및 $157{\times}10^6CFU/g-624{\times}10^6CFU/g$의 미생물밀도를 나타냈다. 인공토양이 25% 및 50% 함유된 혼합토양에서는 참싸리 줄기 및 뿌리생장이 대조구토양보다 높게 나타났고 참싸리의 생장에 영향을 미치는 토양 인자는 용적밀도, 공극률, 수분보유력, 탄질비, 유기물함량 및 미생물함량으로 나타났다.

• Clinical and Experimental Pediatrics
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• 제54권5호
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• pp.207-211
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• 2011

Purpose: This study was conducted to investigate the immune responses of children with moderate and severe novel influenza A virus (H1N1) pneumonia, and to compare their clinical and immunological findings with those of control subjects. Methods: Thirty-two admitted patients with H1N1 pneumonia were enrolled in the study. The clinical profiles, humoral and cell-mediated immune responses of the 16 H1N1 pneumonia patients who were admitted to the pediatric intensive care unit (severe pneumonia group), 16 H1N1 pneumonia patients admitted to the pediatric general ward (moderate pneumonia group) and 13 control subjects (control group) were measured. Results: Total lymphocyte counts were significantly lower in patients with H1N1 pneumonia than in the control group (P=0.02). The number of CD4+ T lymphocytes was significantly lower in the severe pneumonia group ($411.5{\pm}253.5/{\mu}L$) than in the moderate pneumonia ($644.9{\pm}291.1/{\mu}L$, P=0.04) and control ($902.5{\pm}461.2/{\mu}L$, P=0.01) groups. However, the number of CD8+ T lymphocytes was significantly higher in the severe pneumonia group ($684.2{\pm}420.8/{\mu}L$) than in the moderate pneumonia ($319.7{\pm}176.6/{\mu}L$, P=0.02) and control ($407.2{\pm}309.3/{\mu}L$, P=0.03) groups. The CD4+/CD8+ T lymphocytes ratio was significantly lower in the severe pneumonia group ($0.86{\pm}0.24$) than in the moderate pneumonia ($1.57{\pm}0.41$, P=0.01) and control ($1.61{\pm}0.49$, P=0.01) groups. The serum levels of immunoglobulin G, immunoglobulin M and immunoglobulin E were significantly higher in the severe pneumonia group than in the 2 other groups. Conclusion: The results of this study suggest that increased humoral immune responses and the differences in the CD4+ and CD8+ T lymphocyte profiles, and imbalance of their ratios may be related to the severity of H1N1 pneumonia in children.

• Journal of Animal Science and Technology
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• 제47권3호
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• pp.481-490
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• 2005

Nitrate contamination in water system is a critical environmental problem caused by excessive application of chemical fertilizer and concentration of livestock. In order to prevent further contamination, therefore, it is necessary to understand the origin of nitrate in nitrogen loading sources and manage the very source of contamination. The objective of this study was to examine the nitrate contamination sources in different agricultural system by using nitrogen isotope ratios. Groundwater and runoff water samples were collected on a monthly basis from February 2003 to November 2003 and analyzed for nitrogen isotopes. The nitrate concentrations of groundwater in livestock fanning area were higher than those in conventional and organic fanning area and exceeded the national drinking water standard of 10mg N/ l. The ${\delta}^{15}N$ranges of chemical fertilizer and animal manure were - 3.7${\sim}$+2.3$\textperthousand$ and +12.5${\sim}$26.7$\textperthousand$, respectively. The higher ${\delta}^{15}N$ of animal manure than those of chemical fertilizer reflected isotope fractionation and volatilization of '''N. The different agricultural systems and corresponding average nitrate concentrations and ${\delta}^{15}N$ values were: conventional farming, 5.47mg/e, 8.3$\textperthousand$; organic fanning, 5.88mg/e, 10.1$\textperthousand$; crop-livestock farming, 12.5mg/e, 17.7%0. These data indicated that whether conventional or organic agriculture effected groundwater and runoff water quality. In conclusions, relationship between nitrate concentrations and ${\delta}^{15}N$ value could be used to make a distinction between nitrate derived from chemical fertilizer and from animal manure. Additional investigation is required to monitor long-term impact on water quality in accordance with agricultural systems.

• 한국물환경학회지
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• 제33권6호
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• pp.689-695
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• 2017

This study was carried out to investigate the physicochemical and adsorptive characteristics of black carbon (BC) materials for cesium in case of severe nuclear accidents. The BC was prepared with a xylem of oak and pine trees incompletely combusted with different ramp rate and final temperature. Carbon (C), hydrogen (H) and oxygen (O) atomic ratios, BET, pore structure, and zeta potential were characterized for the produced BC. A low cesium concentration ($C_w{\approx}10^{-7}M$) was used for sorption batch experiments. The H/C and O/C ratios of BC decreased with the increase of final temperature, which indicates a carbonization of the wood materials regardless of ramp rate and tree species. However, SEM images showed different pore structures depending on tree species such as steric and plate-like for oak-BC and pine-BC, respectively. The greatest sorption distribution coefficients of $K_{d,Cs}{\approx}1,200{\sim}1,800L\;kg^{-1}$ were observed for the oak-BC produced at $400^{\circ}C$, while comparatively low $K_{d,Cs}$ < $100L\;kg^{-1}$ for pine-BC. In addition, the sorption capabilities of BC declined with the increase of combustion temperature up to $600^{\circ}C$, because high temperature destroyed surface functionalities with the rise of ash components in the BC. Therefore, the sorption processes of BC for radioactive cesium are predominantly controlled by final production temperature of BC as well as raw materials (e.g., tree species).