• Title/Summary/Keyword: Pak-Choi

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Gottlieb groups of spherical orbit spaces and a fixed point theorem

  • Chun, Dae Shik;Choi, Kyu Hyuck;Pak, Jingyal
    • Bulletin of the Korean Mathematical Society
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    • v.33 no.2
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    • pp.303-310
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    • 1996
  • The Gottlieb group of a compact connected ANR X, G(X), consists of all $\alpha \in \prod_{1}(X)$ such that there is an associated map $A : S^1 \times X \to X$ and a homotopy commutative diagram $$ S^1 \times X \longrightarrow^A X $$ $$incl \uparrow \nearrow \alpha \vee id $$ $$ S^1 \vee X $$.

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21세기를 향한 유역 수문학

  • Yun, Gang-Hun;Choi, Han-Gyu;Choi, Yeong-Pak
    • Water for future
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    • v.23 no.1
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    • pp.6-20
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    • 1990
  • 산업이 고도로 발전하면서 많은 나라들은 인간의 생활 환경을 인간과 자연이 조화로운 삶을 영위할 수 있는 공원과 같은 생활공간으로 개발하기 위하여 많은 부존자원을 이용하고 있다. 이들 자원중에서 수자원은 쾌적한 생활공간을 조성하기 위한 가장 중요한 것으로서, 효율적인 수자원 이용을 위하여 물의 사용량 결정, 사용량 평가 등에 관한 사항들을 정량화하기 위하여 수문모형을 사용하고 있다. 본 논문은 독일의 Karlsruhe 대학의 Institute for Hydrology and Water Resourced Planning(IHW)에서 수행된 연구에 기초를 두고 있는 것으로서 장래의 강우-유출 모형개발을 고찰하였다.

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Determination of Aldehydes in Tap Water by Reverse Phase Liquid Chromatography (역상 액체 크로마토그래피에 의한 수도수 중 알데하이드류의 정량)

  • Choi, Yong Wook;Choi, Yun Jung
    • Journal of the Korean Chemical Society
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    • v.43 no.4
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    • pp.438-446
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    • 1999
  • The optimum analytical method of aldehydes, ozone by-products, was established by reverse phase liquid chromatography. Six aldehydes including formaldehyde, acetaldehyde, acrolein, propionaldehyde, butylaldehyde and benzaldehyde, and one ketone including acetone were selected as aldehyde test samples through preliminary experiments. Such analytical conditions as the pH of citrate buffer solution, reaction temperature, reaction time, and concentration of DNPH, the component and composition of desorption solvent were optimized. As the result, pH 3.0 of citrate buffer solution, 40$^{\circ}C$ of reaction temperature, 15 minutes of reaction time, and 0.012% of DNPH concentration were chosen as optimum conditions. Aldehydes-DNPH derivatives in water were concentrated on $C_18$ Sep-Pak cartridge and followed by elution of their derivatives fraction with THF/ACN(70/30) mixture, and showed recoveries of the range from 87 to 107%. Separation condition on Nova-Pak $C_18$ column with low pressure gradient elution from ACN/MeOH/water(30/10/60) of an initial condition to 80% ACN of a final condition was found to give a good resolution within 20 minutes of run time. 86% to 103% of recovery for aldehydes using this method was similar to that for aldehyde using EPA Method 554 which is ranged from 84% to 103%.

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Yield and Nutritional Quality of Several Non-heading Chinese Cabbage (Brassica rapa var. chinensis) Cultivars with Different Growing Period and Its Modelling

  • Kalisz, Andrzej;Kostrzewa, Joanna;Sekara, Agnieszka;Grabowska, Aneta;Cebula, Stanislaw
    • Horticultural Science & Technology
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    • v.30 no.6
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    • pp.650-656
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    • 2012
  • The aims of the experiment, conducted over three years in the Central Europe field conditions, were (1) to investigate the effect of growing period (plantings in the middle and at the end of August: $1^{st}$ and $2^{nd}$ term, respectively) on yield and chemical composition of the non-heading Chinese cabbage (Brassica rapa var. chinensis) cultivars 'Taisai', 'Pak Choy White', and 'Green Fortune', and (2) to develop regression models to evaluate the changes in crop yields as a function of weather conditions. A highest marketable yield was obtained from 'Taisai' (65.71 and 77.20 $t{\cdot}ha^{-1}$), especially in the $2^{nd}$ term of production. Low yield, observed for 'Pak Choy White' was due to its premature bolting. Almost 39% ($1^{st}$ term) and 70% ($2^{nd}$ term) of plants of this cultivar formed inflorescence shoots before harvest. The highest dry matter level was observed in the leaf petioles of 'Taisai', while 'Green Fortune' was the most abundant of carotenoids and L-ascorbic acid. The content of soluble sugars was the lowest for 'Pak Choy White'. In a phase of harvest maturity, more of the analyzed constituents were gathered by plants from earlier plantings, and differences were as follows: 4.7% (dry matter), 26.3% (carotenoids) and 22.1% (L-ascorbic acid), in comparison to $2^{nd}$ term of production. Significant increase of soluble sugars level was observed for plants from later harvest. The regression model for marketable yield of Chinese cabbage cultivar 'Taisai' as a function of maximum air temperature can predict the yield with accuracy 68%. The models for yield or bolting of 'Pak Choy White', based on extreme air temperatures and sunshine duration, were more precise (98%). It should be pointed out that Taisai could be recommended for later growing period in Central Europe conditions with regard to maximum yield potential. 'Green Fortune' was notable for its uniform yielding. To obtained plants of higher nutritional value, earlier time of cultivation should be suggested. Described models can be successfully applied for an approximate simulation of Chinese cabbage yielding.

Determination of global ice loads on the ship using the measured full-scale motion data

  • Lee, Jae-Man;Lee, Chun-Ju;Kim, Young-Shik;Choi, Gul-Gi;Lew, Jae-Moon
    • International Journal of Naval Architecture and Ocean Engineering
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    • v.8 no.4
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    • pp.301-311
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    • 2016
  • This paper describes the whole procedures to determine ice-induced global loads on the ship using measured full-scale data in accordance with the method proposed by the Canadian Hydraulics Centre of the National Research Council of Canada. Ship motions of 6 degrees of freedom (dof) are found by processing the commercial sensor signals named Motion Pak II under the assumption of rigid body motion. Linear accelerations as well as angular rates were measured by Motion Pak II data. To eliminate the noise of the measured data and the staircase signals due to the resolution of the sensor, a band pass filter that passes frequencies between 0.001 and 0.6 Hz and cubic spline interpolation resampling had been applied. 6 dof motions were computed by the integrating and/or differentiating the filtered signals. Added mass and damping force of the ship had been computed by the 3-dimensional panel method under the assumption of zero frequency. Once the coefficients of hydrodynamic and hydrostatic data as well as all the 6 dof motion data had been obtained, global ice loads can be computed by solving the fully coupled 6 dof equations of motion. Full-scale data were acquired while the ARAON rammed old ice floes in the high Arctic. Estimated ice impact forces for two representative events showed 7e15 MN when ship operated in heavy ice conditions.

Effect of Root Zone Restriction on the Growth Response and Phytonutrients Contents of Leafy Vegetables Grown in a DFT System (담액 수경재배시 근권제한이 엽채류의 생육 및 식물 영양소 함량에 미치는 영향)

  • Seo, Tae-Cheol;Rhee, Han-Cheol;Yun, Hyung-Kwon;Chun, Chang-Hoo
    • Horticultural Science & Technology
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    • v.28 no.3
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    • pp.415-422
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    • 2010
  • Two leaf lettuces, chicory, endive, edible chrysanthemum, and pak-choi were hydroponically cultured under root restricted conditions in a deep flow technique system and their growth and nutritional values were investigated. Cylindrical plastic tubes with 100 mm height and diameters of 20, 25 or 30 mm were used for root restriction. Growth of all species was retarded by 25-95% as the roots zone was restricted. Pak-choi and edible chrysanthemum showed greater reduction in growth as compared with chicory and endive. Percent dry matter, C/N ratio, and contents of total ascorbic acid and total anthocyanin increased in the root restricted treatments. Contents of P and K decreased in the root restricted treatments, while contents of Mg, Fe, Mn, and Zn were not consistent among the tested species. Optimized root volumes to improve the nutritional values and to reduce the growth retardation varied depending on species of leafy vegetables. Tubes of ${\Phi}25mm{\times}100mm$ and ${\Phi}30mm{\times}100mm$ were suitable for chicory, endive and lettuce, and edible chrysanthemum and pak-choi, respectively. Results indicate that nutritional values of hydroponically-cultured leafy vegetables can be improved by root restriction.