• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2004.10a
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• pp.274-277
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• 2004

Fuel/air mixing in air turbo ramjet(ATR) combustor is a significant parameter of combustion stability and efficiency. In this study, fuel distribution in the ATR model combustor was measured to compare the degree of mixing with respect to the velocity ratio$(r=v_a/v_f)$ between fuel gas and air. Planar laser-induced fluorescence(PLIF) and image processing method were used to obtain two dimensional fuel distribution. Fuel mixing went bad with approaching to r=1.

• Polymer(Korea)
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• v.24 no.1
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• pp.8-15
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• 2000

Phenolic/furfural(P/F) gel microspheres were successfully produced by new supercritical $CO_2$-based process. $CO_2$-soluble poly(dimethylsiloxane) (PDMS) was used as the stabilizer in this system. Spherical morphology of the gel microspheres was confirmed by scanning electron microscopy. Particle size and particle size distribution of P/F gel microspheres can be modified by variety of the solids content and the stabilizer content. The resultant P/F gel microspheres have average particle size in the range of 1-6 ${\mu}{\textrm}{m}$. The structure of P/F gel microspheres was revealed by thermogravimetric analysis and IR analysis.

• Korean Journal of Agricultural and Forest Meteorology
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• v.17 no.3
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• pp.227-235
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• 2015

Using eddy covariance method, net ecosystem exchange (NEE) of $CO_2$ ($F_{CO_2}$), $H_2O$ (LE), and sensible heat (H) can be approximated as the sum of eddy flux ($F_c$) and storage flux term ($F_s$). Depending on strength and distribution of sink/source of scalars and magnitude of vertical turbulence mixing, the rates of changes in scalars are different with height. In order to calculate $F_s$ accurately, the differences should be considered using scalar profile measurement. However, most of flux sites for agricultural lands in Asia do not operate profile system and estimate $F_s$ using single-level scalars from eddy covariance system under the assumption that the rates of changes in scalars are constant regardless of the height. In this study, we measured $F_c$ and $F_s$ of $CO_2$, $H_2O$, and air temperature ($T_a$) using eddy covariance and profile system (i.e., the multi-level measurement system in scalars from eddy covariance measurement height to the land surface) at the Chengmicheon farmland site in Korea (CFK) in order to quantify the differences between $F_s$ calculated by single-level measurements ($F_s_{-single}$ i.e., $F_s$ from scalars measured by profile system only at eddy covariance system measurement height) and $F_s$ calculated by profile measurements and verify the errors of NEE caused by $F_s_{-single}$. The rate of change in $CO_2$, $H_2O$, and Ta were varied with height depending on the magnitudes and distribution of sink and source and the stability in the atmospheric boundary layer. Thus, $F_s_{-single}$ underestimated or overestimated $F_s$ (especially 21% underestimation in $F_s$ of $CO_2$ around sunrise and sunset (0430-0800 h and 1630-2000 h)). For $F_{CO_2}$, the errors in $F_s_{-single}$ generated 3% and 2% underestimation of $F_{CO_2}$ during nighttime (2030-0400 h) and around sunrise and sunset, respectively. In the process of nighttime correction and partitioning of $F_{CO_2}$, these differences would cause an underestimation in carbon balance at the rice paddy. In contrast, there were little differences at the errors in LE and H caused by the error in $F_s_{-single}$, irrespective of time.

• Journal of Korea Water Resources Association
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• v.36 no.6
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• pp.1035-1046
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• 2003

In order to evaluate the TOPMODEL's prediction ability for spatial distribution of water table depths, two major assumptions and governing equation of water table depth are tested. For the test, data of hydrological observations are used and a soil survey is made in the steep hillslope with thin soils. Responses of water table and hydraulic properties of soil are coincident with two major assumptions of the TOPMODEL's such as water table gradient parallel to the local topographical slope and exponential decline in transmissivity with depths. Soil texture and the decline rate of transmissivity(f) we homogeneous in space at the 0∼0.3m depths of the soil of the hillslope, but they are heterogeneous in space below its 0.3m depths due to the vertical change of soil texture and the ‘f’. It is shown that the TOPMODEL's equation can be used for simulating distribution of water table depth at the depths with uniform values of the 'f'.

• Korean journal of applied entomology
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• v.12 no.2
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• pp.79-82
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• 1973

1. In order to investigate Physiologic races of Puccinia gramininis f. sp. tritici as basic materials for tile breeding of resistant varieties to stem rust of wheat, this experiment was carried out during 1971 and 1973. 2. Twenty seven isolates of the fungus were identified as follows: two isolates of race 11, eight . isolates of race 17, and 21, four isolates of race 34, one each of race 37 and 56, respectively The remaining three isolates identified were not identical with the key issued by Stakman, et at in 1962. Therefore, the three new races were tentatively numbered $K_3,\;K_4\; and\; K_4,$ in addition to $K_l\;and\;K_2$ described in 1961. 3. Therefore, attempts to produce resistant varieties to stem rust of wheat should be accompanied by intensive investigation of Physiologic races of p. graminis f. sp. tritici in the future.

• Korean Journal of Plant Tissue Culture
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• v.21 no.1
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• pp.35-39
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• 1994

Is obtain cell lines showing high level of rice cold tolerance, direct in vitro selection through cold stress on primary pollen callus derived from anther culture was carried out Genotypic difference in callus formation and plant regeneration was recognized Rates of albino was increased along the duration of cold stress. Reciprocal effects were not noticed in anther culturability There was no variants related to rice leaf discoloration in pollen derived lines from parental varieties, regardless of days of cold stress. The regeneration and recombination of rice leaf discoloration in 146 pollen-derived lines, 70 pollen-derived lines from cold stress at $0^{\circ}C$ for 10 days, and 830 F$_2$ plants presented normal distribution curves with skewness in tolerance and no significant difference among 3 populations. Direct in vitro selection for rice cold tolerance through cold stress on primary pollen callus derived from anther culture, therefore, was revealed ineffective as a in vitro technology.

• Proceedings of the KWS Conference
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• 2001.10a
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• pp.202-205
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• 2001

• Journal of the Korean Society for Nondestructive Testing
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• v.18 no.1
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• pp.1-9
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• 1998

The attenuation of acoustic emission (AE) waves was evaluated for injection-molded short-fiber-reinforced thermoplastic composites employing simulated AE waves. Values of attenuation coefficient (${\alpha}$) decreased more with increasing fiber volume fraction ($V_f$) than that expected from a simple linear relation between ${\alpha}$ and $V_f$. The effect of wave attenuation was taken into account in a quantitative analysis of the AE peak amplitude distribution which was obtained from each zone partitioned in a specimen gage portion. The amplitude distribution compensated for the measured attenuation loss was exhibited almost similar in every zone of the specimen. Consequently, it was, shown that the AE amplitudes obtained from fiber/plastic composites were considerably affected by the attenuation.

• Proceedings of the Plant Resources Society of Korea Conference
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• 2018.04a
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• pp.35-35
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• 2018

터리풀속(Filipendula)은 장미과(Rosaceae), 장미아과(Rosoideae)에 속하는 다년생 초본이며, 북반구 온대지역의 산지지역에 서식하며 15-20여 종이 보고되어 있고, 이 중 10여종이 한국, 중국, 일본, 타이완 등의 동아시아 지역에 분포한다. 본 연구의 목적은 DNA 염기서열 자료를 이용하여 터리풀속(Filipendula)내 종들간의 계통관계를 규명하기 위하여 본 연구를 수행하였다. 이를 위해서 11종 29개체의 터리풀속(Filipendula)샘플과 외군인 산딸기나무속(Rubus)에 속하는 3종 5개체의 샘플을 이용하였다. 추가로 Genbank에서 3속 10종 18개의 염기서열을 다운받아 비교분석에 이용하였다. 계통연구를 위하여 엽록체에 존재하는 atpF-atpH, psbK-psbI, psbA-trnH, matK, rbcL, 5개 마커와 핵에 존재하는 ITS, 총 6개 마커의 염기서열을 생산하였다. 총 52개의 샘플에 대하여 엽록체유전체 5개 마커지역은 염기서열 길이가 3,485bp였고 핵 ITS지역은 631bp였으며, 이들을 합한 염기서열 길이는 4,116bp였다. 계통분석결과, 터리풀속(Filipendula)은 단계통군을 이루었다. F. occidentalis와 F. vulgaris가 기저분류군을 이루었고 이들은 각각의 아속에 해당한다. 그리고 나머지 종들은 모두 하나의 단계통군을 이루었다. 위의 결과들은 1961년 시미즈가 본 속을 Hypogyna아속, Filipendula아속, Ulmaria아속으로 나눈 분류시스템과 일치한다. 나아가 분자계통수에서 Ulmaria아속은 크게 4개의 subclade로 구분되었다. 먼저 subclade I에는 F. vestita, F. kiraishiensis, F. tsuguwoi, F. multijiuga, F. purpurea 등 5개 종으로 구성되었다. Subclade II는 F. ulmaria 한 종으로만 구성되었다. Subclade III에는 F. glaberrima, F. koreana, F. formosa, F.camtschatica 로 구성되었으며 subclade III에는 한국에 서식하는 3종이 포함되었다. Subclade IV에는 F. rubra, F. angustiloba, F. palmata, F. intermedia 4종으로 구성되었다. 이번연구에서는 Ulmaria아속내에 4개의 subclade가 존재함이 처음으로 확인되었다.

• Journal of Food Hygiene and Safety
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• v.35 no.3
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• pp.271-278
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• 2020

Enterotoxigenic Escherichia coli is one of the major causative infectious agents of diarrhea in newborn and post-weaning pigs and leads to a large economic loss worldwide. However, there is limited information on the distribution and characterization of virulence genes in E. coli isolated from diarrheic piglets, which also applies to the current status of pig farms in Korea. To investigate the prevalence and characterization of virulence genes in E. coli related to diarrhea in piglets, the rectal swab samples of diarrheic piglets (aged 2 d to 6 w) were collected from 163 farms between 2013 and 2016. Five to 10 individual swab samples from the same farm were pooled and cultured on MacConkey agar plates, and E. coli were identified using the API 32E system. Three sets of multiplex PCRs were used to detect 13 E. coli virulence genes. As a result, a total of 172 E. coli isolates encoding one or more of the virulence genes were identified. Among them, the prevalence of individual virulence gene was as follows, (1) fimbrial adhesins (43.0%): F4 (16.9%), F5 (4.1%), F6 (1.7%), F18 (21.5%), and F41 (3.5%); (2) toxins (90.1%): LT (19.2%), STa (20.9%), STb (25.6%), Stx2e (15.1%), EAST1 (48.3%); and (3) non-fimbrial adhesin (19.6%): EAE (14.0%), AIDA-1 (11.6%) and PAA (8.7%), respectively. Taken together, various pathotypes and virotypes of E. coli were identified in diarrheic piglets. These results suggest a broad array of virulence genes is associated with coliform diarrhea in piglets in Korea.