• Journal of the Korea Organic Resources Recycling Association
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• v.11 no.3
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• pp.87-95
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• 2003

Although extensive studies were conduced on hydrogen fermentation of organic wastewaters, little is known about biohydrogen production from organic solid wastes. The leaching-bed reactor treating food waste by heat-shocked anaerobic sludge was, therefore, operated at D of 2.1, 3.6, 4.5 and $5.5d^{-1}$ to find optimal D for hydrogen production. Successful operation of a reactor can be accomplished when it is operated at proper dilution rate (D). Operation at high D leads to the washout of biomass in the reactor while operation at low D leads to product inhibition due to the accumulation of excess VFA. These appear to limit the production of hydrogen to reach a higher level. All the reactors showed that, on day 1-3, hydrogen production was dominant and VFA concentration was higher than ethanol. Butyrate and acetate were major components of VFAs over the whole operation, though lactate was very high on day 1-2. Compared with other D values, D of $4.5d^{-1}$, resulted in higher butyrate/acetae (B/A) ratios during the fermentation. The trend of B/A ratios was similar to the hydrogen production, suggesting that butyrate formation favored hydrogen production. Ethanol increased significantly from day 4 when hydrogen Production stopped. It indicated that heat-shocked sludge was able to induce a metabolic flow from hydrogen-and acid-producing pathway to solvent-producing pathway. Operation at D of $4.5d^{-1}$ led to higher fermentation efficiency (58%) than those (51.5, 55.3 and 53.7%) at 2.1, 3.6 and $5.5d^{-1}$. The COD removed was convened to hydrogen (10.1%), VFA (30.9%), and ethanol (17.0%).

• Korean Journal of Food Science and Technology
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• v.20 no.1
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• pp.13-18
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• 1988

Retrogradation characteristics of 1% dilute rice starch dispersion were analyzed. The retrogradation was increased with prolonged storage, however, the trend in increase was more conspicuous during the initial phase of retrogradation period. The Avrami exponent, rate constant, and time constant of 1% dilute Chuchong starch dispersion were 0.96, 0.21 $days^{-1}$, and 4.77 days, respectively As the Avrami exponent approaches unity (n=1), it is confirmed that the dilute rice starch dispersion retrogrades following the formation of a rod-like growth of crystals from instantaneous nuclei. When the retrogradation process of dilute rice starch dispersion was traced, the three-dimensional structure of crystals which had different contour from native stach was formed.

• Proceedings of the KAIS Fall Conference
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• 2004.06a
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• pp.278-280
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• 2004

본 연구에서는 아산시의 모종처리구역을 대상으로 합류식 하수관거 월류수의 발생특성을 파악하고자 유량 및 오염물질 발생경향, 오염물질별 상관관계 등에 대하여 살펴보았다. 조사 결과, 강우시 월류 발생초기의 오염물질의 농도는 강우에 의한 초기세척현상(First Flush)에 의해 상당히 높게 나타났으며, 강우초기의 높은 오염물질의 농도는 강우에 의해 희석되어 일시적으로 낮아졌다가 높은 강우강도에 의하여 급격히 상승하였으며, 이후 오염물질의 농도는 유량의 감소에 따라 점차적으로 감소하는 것으로 나타났다. 또한 수질항목별 상관계수를 보면, SS와 TP의 상관계수가 가장 크게 나타났으며, COD와 TP, SS와 COD의 순으로 상관계수가 높은 것으로 나타났다.

• 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 Sericultural and Entomological Science
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• v.37 no.2
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• pp.188-190
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• 1995

The eggs of the silkworm, Bombyx mori, were treated topically with 10-3, 1-0-4, 10-5 aqueous Insegar and the hatchability was checked. The chemical affected all the tested developmental stages, but the results varied according to the stages and the degree of density. The hatchability was reduced upto 0% for the eggs treated at the 1 and 3 day stages, compared to 97% of control eggs.

• Journal of Ginseng Research
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• v.11 no.1
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• pp.66-76
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• 1987

When rice seeds were rinsed in If) Korean ginseng tea (KG 722, Korean Ginseng Product Co. Ltd. made) for 28 hours prior to seeding, the early growth was found relatively fast and their resistance against blight and harmful insects was increased. Rice yield showed that control group, rinsing group and spraying group were 514 kg/10a, 562 kg/ 10a and 571 kg/ 10a respectively. However, rinsing and spraying groups were 590 kg/ 10a (leaf spraying) and 605 kg/ 10a (spray immediate after seeding) respectively.

• Journal of Radiation Protection and Research
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• v.23 no.1
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• pp.1-6
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• 1998

A diffusion model of radioactive liquid effluents is developed and applied for YGN NPP's site, based on the Gaussian plume type model. Due to the complexity of oceanic diffusion characteristics of YGN site, a simple and reliable statistical model based on Reg. Guide 1.113 is developed. Also, a computer code package to calculate dilution factors as a function of plant operation conditions and pathway of radioactive materials. A liquid effluents diffusion model is developed by dividing the diffusion range into two categories, i. e, a near field mixing region and a far field mixing region. In the near field, the initial mixing is affected by a buoyance force, a high initial turbulence and momentum which is characterized by a plant operation condition and environmental conditions. The far field mixing is similar to gaseous effluents diffusion. So, beyond the near field region, wellknown Gaussian plume model was adopted. A different area averages of Gaussian plume equation was taken for each radioactive exposure pathway. As a result, we can get different dilution factors for different pathways. Results shows that present dilution factors used for YGN ODCM is too much overestimated compared with dilution factors calculated with the developed model.

• Korean Journal of Microbiology
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• v.35 no.3
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• pp.237-241
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• 1999

Phenolic resin wastewater contained 41,000 mglI phenol, 2,800 mg/l fonualdehyde and various chlorinated phenolic compounds. Candida tropicalis PW-51 isolated [rom the natural enVlfooment was able to degrade 1,000 mg/l phenol in the presence of 100 mglI formaldehyde, but it took much time to degrade phenol with the increase of formaldehyde in phenolic resin wastewater. %en the phenolic resin wastewater was diluted to 1/40, the initial concentration of phenolic compounds (phenols) was 882 mglI and degraded to 81 mglI by C tfVpicalis PW-51 in batch culture. In a continuous biological treatment, the phenolic resin wastewater was diluted to 40 (745 mglI), 20 (1,356 mglI), or 10 (2,875 mglI) times. The removal efficiency of phenols in 1/40- and lI20-diluted phenolic resin wastewater was about 92%, but the phenols in 1!1O-diluted wastewater were not degraded. The remained phenols in wastewater were absorbed by a mixture of activated carbon and rice bran (1:1, v:v) in the process of absorption which was connected to the biological treatment. The total removal efficiency of phenols in 1!40~ and l/20-diluted phenolic resin wastewater was 99.9%.

• Microbiology and Biotechnology Letters
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• v.16 no.6
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• pp.510-516
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• 1988

The effects of input substrate concentration and dilution rate on mass transfer resistance in the operation of immobilized cell reactors were investigated using Rhodospirillum rubrum KS-301 immobilized by Ca alginate as reactor element and glucose as growth-limiting substrate. The kinetic parameters were obtained to estimate effectiveness factors. In the packed-bed reactor, internal mass transfer resistance was predominating although external resistance could not be neglected. The overall effectiveness factor was decreased with increase of dilution rate. In the continuous stirred-tank reactor, external resistance was nearly neglected and the overall effectiveness factor was not affected by dilution rate. In this experiment the overall effectiveness factors in PBR and CSTR were estimated to be 0.70 and 0.71 at D$_{i}$ = 0.2/h, R = 0.15 cm, and S$_{i}$ : 1.0g/L, respectively.

• Journal of the Korea Organic Resources Recycling Association
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• v.10 no.2
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• pp.65-70
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• 2002

The previous studies showed that rumen microorganisms had an enhanced waste-degrading capability and controlling the dilution rate was very effective in improving acidification efficiency. Generally the composition of food waste has a small deviation value, but one of the waste components (grains, vegetables or meats) can be increased dramatically depending on a seasonal variation. Thus, it is important to evaluate the efficiency of acidogenic fermentation in this case. Each component was spiked to be 80% of the total waste in R1 (grains), R2(vegetables), and R3 (meats). In Rl, rapid degradation occurred during the initial two days. R2 showed similar performance to that of general food waste. In R3, degradation retarded in the initial stage and then increased after controlling the dilution rate. The acidification efficiencies of the reactors were 88.7 (R1), 73.5 (R2), and 62.1% (R3), respectively. Therefore, the fermentation efficiency was kept over 62% regardless of waste components, indicating that it was stable to acidify food waste by employing rumen microorganisms and controlling the dilution rate.