• Proceedings of the Korea Water Resources Association Conference
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• 2009.05a
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• pp.880-884
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• 2009

여름철 강우시 저수지로 유입하는 고탁도의 하천수는 저수지 주변 수체에 비해 낮은 수온과 높은 부유물질 농도(SS)로 인해 상대적으로 높은 밀도를 가지며, 저수지 내에서 동일 밀도층을 따라 분포하며 밀도류를 형성하게 된다. 탁수는 대부분 장기간 저수지에 체류하며 수질과 수생태계에 큰 영향을 주게 된다. 따라서 저수지로 유입한 탁수의 밀도류 거동특성을 파악하는 것은 저수지 운영, 수질관리 및 수생태계 보호를 위한 관리대책 수립에 있어서 중요한 요소이다. 본 연구의 목적은 횡방향 평균 2차원 수치모델을 이용하여 초기수위별 다양한 유량규모에서 소양호로 유입하는 밀도류의 거동특성(유입경계지점 수심($h_0$), 침강점 수심($d_p$)과 거리($X_p$), 분리점 수심($d_s$), 중층류 관입두께($h_i$), 댐 축 도달시간($t_a$), 희석율(${\beta}$))을 분석하여 저수지 수질관리를 위한 의사결정지원 기초정보를 제공하는데 있다. 밀도류의 거동분석을 위해 사용된 유량조건은 그동안 소양호에서 발생한 홍수크기를 바탕으로 7개의 등급으로 나누었으며, 각각의 유량조건별 수문곡선은 2007년 수문사상 중 7월 30일부터 8월 30일까지의 수문사상을 바탕으로 수정가우시안 공식을 사용하여 산정하였다. 탁수 거동 특성의 모의는 서로 다른 초기 수위 및 유량조건하에서의 탁수거동을 나타냈고, SS농도 25 mg/L 이상을 기준으로 하여 탁수층의 $d_p$, $X_p$, $d_s$, $h_i$, $t_a$, ${\beta}$를 산정하였다. 일반적으로 유량규모가 커질수록 $d_p$와 $d_s$는 증가하였고, $X_p$는 댐 축으로부터 가까워짐이 확인되었으나, 동일 유량규모에 대해 초기 수위가 증가함에 따라 $X_p$는 대체로 댐으로부터 멀어졌다. $h_i$는 유량규모가 증가함에 따라 완만하게 증가하는 경향을 보였고, $t_a$는 초기수위가 EL. 165 m일 때 유량이 2,000 CMS 미만인 경우 댐 앞까지 도달하지 못하는 것으로 나타났으며, 나머지 수위조건에서는 유량이 3,000 CMS 미만인 경우 댐 앞까지 도달하지 못하는 것으로 나타났다. 유량 규모에 따라 $X_p$가 0 km인 지점과 19 km인 지점에서의 ${\beta}$ 값을 산정한 결과 일반적으로 유량규모가 커질수록 유입수의 희석효과는 작아지며 초기수위가 커질수록 증가하는 경향을 나타냈다. 연구 결과는 탁수 발생 초기 저수지 운영 실무자들이 유량규모 및 초기 수위조건에 따른 밀도류의 거동특성을 신속히 예측하는 목적으로 사용될 수 있다.

• Journal of the Korean Society of Food Science and Nutrition
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• v.33 no.3
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• pp.553-559
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• 2004

This study was carried out to estimate the effects of glucono-$\delta$-lacton (GDL) on prolongation of shelf-life on Kimchi. Final concentration of added GDL was determined 0.3% according to the result of sensory evaluation. Chemical characteristics and microbiological parameters were monitored during fermentation at 1$0^{\circ}C$. GDL Kimchi showed the initial sharp decrease in pH and gradually increase of pH due to osmotic pressure and then the pH of GDL Kimchi was slowly decreased compared with that of control Kimchi during fermentation. The acidity of control Kimchi was markedly increased around pH 4.5 by growth of microorganism. Otherwise, GDL Kimchi showed that t]le formation of organic acids was slow and little amount compared with that of control Kimchi. HPLC analysis showed oxalic acid, lactic acid, acetic acid, malic acid and succinic acid appeared by fermentation. The production of lactic acid changed a lot in control Kimchi, where as little in GDL Kimchi. Growth of L. mesenteroides at initial stage of Kimchi fermentation was remarkably inhibited by adding 0.3% GDL. It retarded also the growth of L. Plantarum and L. breuis at late stage of Kimchi fermantation and led to reduce the softening of texture and retard over ripening of Kimchi. Tn sensory evaluation of Kimchi, GDL Kimchi showed the similar characteristics to the control Kimchi. This result suggested that GDL can be successfully used for the prolongation of shelf-life and sensory evaluation on Kimchi.

• Korean Journal of Soil Science and Fertilizer
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• v.39 no.2
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• pp.73-79
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• 2006

Aeration is the most important and indispensable operation unit for the treatment of swine manure using aerobic liquid-composting process. The composting of swine manure depends on biological treatment process, but the highly concentrated ammonia nitrogen is required a pretreatment to expect the appropriate efficiency of the biological treatment process. In this study, pilot experiments have been carried out to estimate of the fit condition about ammonia stripping process as a pretreatment to aerobic liquid- composting. pH adjustment with $Ca(OH)_2$ was economically superior to use of NaOH and optimum pH of ammonia stripping was 12.3, ammonia nitorgen was rapidly removed as pH were increased at $$35^{\circ}C$$. When air stripping is performed before aerobic liquid-stripping, a high initial pH is required for complete ammonia removal and is additional effects such as organic substances, phosphorus, turbidity, and color removal. Stripping process was very efficient in the pretreatment of highly concentrated ammonia nitrogen for composting of swine manure. Emission rate of gaseous ammonia was $0.5355mole\;s^{-1}$ at initial time and $0.0253mole\;s^{-1}$ at finitial time. The fit condition of ammonia stripping in this study were at the temperature of $$35^{\circ}C$$, and the pH of 12.3 during 48 hours.

• Journal of Korean Society of Environmental Engineers
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• v.37 no.4
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• pp.234-239
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• 2015

Various leaching tests were applied to the soil affected by accidental leakage of HF in an industrial area in Korea. Three different leaching methods including pH-stat, continuous batch leaching, and column tests were adopted to assess leaching characteristics and mobility of fluorine(F) in soil and the potential risks to ecosystem. Both natural and spiked samples were used for the leaching tests. F concentrations in the batch tests increased by leaching rapidly in the early stage of leaching and then maintained rather constant levels. Column leaching test also show similar result to that of the batch test. pH also controlled the leaching behavior of the soil. With increasing pH, more F was released in the pH-stat test. This is mainly due to the competition and exchange with hydroxyl ions, as pH increase to the alkaline range. Most of the F released by the accident seem to have removed in the very early stage of leaching, whereas some natural proportion from soil minerals are thought to have been released very slowly. Therefore, little F released during the accident remained, based on the results of this study on the samples after two years of the accident. We could conclude that soil contaminated by external effects such as chemical accidents should be managed immediately, especially with F.

• Korean Journal of Food Science and Technology
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• v.36 no.2
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• pp.349-354
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• 2004

Predictive growth model of Vibrio parahaemolyticus in modified surimi-based imitation crab broth was investigated. Growth curves of V. parahaemolyticus were obtained by measuring cell concentration in culture broth under different conditions ($Initial\;cell\;level,\;1{\times}10^{2},\;1{\times}10^{3},\;and\;1{\times}10^{4}\;colony\;forming\;unit\;(CFU)/mL$; temperature, 15, 25 37, and $40^{\circ}C$; pH 6, 7, and 8) and applying them to Gompertz model. Microbial growth indicators, maximum specific growth rate (k), lag time (LT), and generation time (GT), were calculated from Gompertz model. Maximum specific growth rate (k) of V. parahaemolyticus increased with increasing temperature, reaching maximum rate at $37^{\circ}C$. LT and GT were also the shortest at $37^{\circ}C$. pH and initial cell number did not influence k, LT, and GT values significantly (p>0.05). Polynomial model, $k=a{\cdot}\exp(-0.5{\cdot}((T-T_{max}/b)^{2}+((pH-pH_{max)/c^{2}))$, and square root model, ${\sqrt{k}\;0.06(T-9.55)[1-\exp(0.07(T-49.98))]$, were developed to express combination effects of temperature and pH under each initial cell number using Gauss-Newton Algorism of Sigma plot 7.0 (SPSS Inc.). Relative coefficients between experimental k and k Predicted by polynomial model were 0.966, 0.979, and 0.965, respectively, at initial cell numbers of $1{\times}10^{2},\;1{\times}10^{3},\;and\;1{\times}10^{4}CFU/mL$, while that between experimental k and k Predicted by square root model was 0.977. Results revealed growth of V. parahaemolyticus was mainly affected by temperature, and square root model showing effect of temperature was more credible than polynomial model for prediction of V. parahaemolyticus growth.

• Microbiology and Biotechnology Letters
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• v.20 no.2
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• pp.203-206
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• 1992

Conditions of fermentation for the production of demethyltetracycline were examined using the mutant, which was obtained through the cell fusion of demeclocycline producing strains, The optimum temperature and the initial pH of broth for demethyltetracycline fermentation were $25^{\circ}C$ and 6.7, respectively. Unlike any other cases, the control of pH with alkali solution during the fermentation process affected the productivity. As a general rule, the larger the inoculum size the higher the early consumption of sugar and the viscosity of broth, which means that fermentation proceeds more rapidly as the inoculum size is increased. The highest productivity was shown when the inoculum size was 5% (v/v), and the phase of seed also influenced the fermentation. Among the parameters of pre-culture thus examined, pH was the most important factor.

• Proceedings of the Korean Institute of Resources Recycling Conference
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• 2005.05a
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• pp.28-32
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• 2005

본 연구는 Karr column을 이용한 희토류원소의 분리에 대한 기초 연구로서, 수상의 초기 pH와 유기상 중 PC-88A의 비누화도에 따른 Nd, Sm의 분리특성을 파악하였다. 실험결과 pH $0.8{\sim}2.3$ 범위에서 PH가 높아짐에 따라 Nd, Sm의 추출율 및 분리계수가 증가하였으며, PC-88A 비누화도 40%인 조건에서 추출 후 수상의 초기 PH에 관계없이 평형 pH가 약 1.5 정도로 유지되는 것을 알 수 있었다. 그리고 PC-88A 비누화도가 증가함에 따라 Nd, Sm의 추출율이 크게 증가하였으며, 비누화도 40%인 조건에서 가장 높은 분리계수(${\beta}_{Sm,\;Nd}\;=\;10.8$)를 보여 주었다.

• Journal of Sericultural and Entomological Science
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• v.33 no.1
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• pp.9-12
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• 1991

A study on dyeing-rate for single and mixture dyeing of silk with acid dyes was carried out. Single and mixture dyeings were performed with levelling and milling dyes at 7$0^{\circ}C$ and at pH 3, pH 4 and pH 5, respectively. The results of this study were summerized as follows : 1. C. I. Acid Orange 7. A) At pH 3, dyeing-rate was more fast in the single dyeing than in mixture dyeing at the beginning of dyeing process. B) At pH 4 and 5, dyeing-rates tend to get very similar in single and mixture dyeing. 2. C. I. Acid Blue 138 A) At all pH value, dyeing-rates were more fast in the mixture dyeing than single dyeing at the beginning of dyeing. B) As the time increased, the difference of dyeing-rate and adsorption amounts between single and mixture dyeing was not shown.

• Korean Journal of Plant Resources
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• v.19 no.4
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• pp.515-516
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• 2006

This experiment was carried out to find out proper culture soil for the flowerpot cultivation of Sedum kamtschaticum. Peatmoss was used for the culture soil. pH of the culture soils were adjusted to 4.5, 5.0, 5.5 and 6.0 using calcium hydroxide. Young plants of Sedum kamtschaticum were planted in the pots of 10cm in diameter. The experiment was conducted by the completely randomized design with 3 replications. Growth characteristics were investigated at intervals of 30 days after planting. As the pH of culture soil is lower, growth of Sedum kamtschaticum showed longer plant height and more number of leaves and branches. pH 4.5 to 5.0 appeared to be optimum range as soil reaction of Sedum kamtschaticum cultivation.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.34 no.2
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• pp.156-159
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• 2001

The experiment was carried out to investigate the productivity of freshwater rotifer, Brachionus calyciflorus and marine rotifer, B. rotundiformis at various temperatures, initial inoculation and pH in a 5 L semi-continuous high density culture. Rotifers were fed by commercial condensed freshwater Chlorella. When pH was not controlled, average daily productions of freshwater and marine rotifers increased with temperature. The highest production, $44\times10^6$ rotifers, was achieved of B. calyciflorus at $32^{\circ}C$ and the possible production lasting period of B. calyciflorus was shorter than that of B. rotundiformis. Under the adjustment of pH at 7, the possible production lasting periods of B. calyciflorus and B. rotundiformis inoculated with 5,000 inds./mL were longer than those of rotifers inoculated with 10,000 inds./mL, and the daily production rate of the former was higher than that of the latter. The results from this study indicated that optimum density of the initial inoculation for the cultivation of B. calyciflorus and B. rotundiformis was 5,000 inds,/mL under the controlled conditions of pH 7 and at $32^{\circ}C$ in a semi-continuous high density culture, in terms of production rate and food cost aspects.