• Applied Chemistry for Engineering
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• v.16 no.2
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• pp.217-225
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• 2005

Because of the limitation of controllable operation variables for the wastewater treatment process with variable hydrodynamic flow patterns, it may preclude the use of this type of nutrient removal activated sludge process. As the operation variables, only temperature and dissolved oxygen (DO) have been used to operate the process. This study made an effort to improve treatment efficiency and operability of the process by the following methodologies: 1) process and operation data analysis using process simulation, 2) determination of optimal control logic or algorithm using a pilot-scaled experimental apparatus and its operations, and 3) application of experimental and simulation results to find the optimal process operation modes. In this study, it was found that the optimal operation mode named 'save mode' in the basis of process variables, such as the ammonia-nitrogen concentration of inlet flow, temperature and flow rate, can reduce the operation cost comparing with the present normal operation mode. And the stable conditions in nitrification were also shown by the proportional control of DO with the inlet air flow rate of blower and the mixing rate of mechanical aeration.

• Korean Journal of Organic Agriculture
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• v.11 no.2
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• pp.103-113
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• 2003

The chemical properties of oak tree wood vinegar and the effect of wood vinegar on the tomato seedling were investigated to apply wood vinegar efficiently to the organic - and natural farming system. On the basis of the results from chemical properties of the oak tree wood vinegar, mineral nutrient contents of wood vinegar was low. Therefore, wood vinegar could not be a suitable nutrient source for the plant growth at 500∼1000 times dilution level. which commonly used in the farming, if only wood vinegar is supplied for the nutrient source for the plant growth. The application of wood vinegar increased root growth up the 500 times dilution level while decreased shoot growth. Furthermore. the anion concentrations such as nitrate and phosphate of the plant were decreased by the application of wood vinegar while cation concentrations such as K. Ca. and Mg were increased. Phenolic compounds of wood vinegar such as chlorogenic acid and ferulic acid enhanced the root growth. Interestingly the application of ferulic acid increased both root and shoot growth at the level of 10$^{-4}$ M concentration. It indicated that the effect of wood vinegar on the production of healthy plant seedling may be due to the beneficial root growth by phenolic compounds such as chlorogenic acid and/or ferulic acid of the wood vinegar. However. the effect of the wood vinegar on the plant growth could be influenced by synergism or antagonism of different phenolic compounds in wood vinegar used. In addition. drench in the soil of wood vinegar may be more beneficial compared to foliar application for the improvement of root activity and plant growth.

• Journal of The Korean Society of Agricultural Engineers
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• v.55 no.4
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• pp.107-119
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• 2013

바이오매스 가스화는 세계적인 증가 추세에 있는 에너지 수요를 충족할 수 있는 기술 중의 하나이다. 바이오매스 가스화를 통해서 농업 폐기물 등 다양한 바이오매스 자원을 에너지로 전환할 수 있고 $CO_2$ 배출량 또한 줄일 수 있다. 본 연구에서는 COMSOL$^{(R)}$ 3.4 소프트웨어를 이용하여 바이오매스 원료와 운전 조건에 따른 가스화 효율 및 합성가스 조성의 변화를 분석하였다. 원료와 구동조건을 최적화하기 위해 가스화 모델을 세우고 원료와 구동조건을 달리하여 합성가스의 성분을 분석 및 예측하였다. 이 모델은 물리적인 실험을 통해 알고 있는 조건을 통해서 합성가스 성분을 시간에 따라 예측할 수 있다. 모델을 이용하여 함수비 5~30 %, 공기중 산소함량 5~50 %, 공기공급 유량 5~45 L/min, 온도 973~1273 K의 조건에서 합성가스의 성분을 예측한 결과 실제 실험 결과와 일치하는 것을 알 수 있다. 모델링 결과 양질의 합성가스를 생산하려면 원료의 회분함량이 적어야 하고 수소 함량이 높은 합성가스를 생산하려면 반응 온도가 높게 유지되고 원료의 함수비가 높아야 한다. 가스화장치의 온도를 높이면 합성가스의 성분 중 CO의 함량이 많아지고, CO의 함량이 많아지면 가스의 발열량이 높아지는 것을 알 수 있다. 또한 CO의 농도가 높고 발열량이 높은 합성가스를 생산하기 위해서는 ER값은 작아야 한다.

• Journal of agriculture & life science
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• v.43 no.4
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• pp.15-20
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• 2009

The transition from pregnancy to lactation, commonly referred to as the "transition period" is characterized by dramatic changes in metabolic processes and their regulation in order to prepare the dairy cow for parturition and lactogenesis. An important adaptation to lactation is the increase in gluconeogenesis by the liver to meet the tremendous increase in demand of glucose for lactose synthesis, and the accumulation of lipid in adipose tissue during pregnancy, its mobilization that begins prior to lactation and the dramatic increase in plasma NEFA concentration early lactation. Epinephrine and insulin, the homeostatic regulators of metabolism are responsible for the adaptations of lipid and carbohydrate metabolism in support of milk production along with mobilization of body fat to meet overall energy demands because dry matter intake is insufficient to meet these demands during early lactation.

• Proceedings of the Korea Water Resources Association Conference
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• 2022.05a
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• pp.179-179
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• 2022

최근 화두가 되고 있는 환경문제 중 하나로 녹조현상을 꼽을 수 있다. 녹조란 남세균이 대량 증식함으로써 물빛이 녹색으로 변하는 현상으로, 영양염류 및 수온 등 이화학적 요소뿐만 아니라체류시간과 같은 수리학적 요인까지 모두 충족되었을 때 발생한다. 심하면 고밀도의 스컴(scum)을 형성하며 독소와 악취를 동반하기도 한다. 유해 남세균이 생성하는 마이크로시스틴(microcystin, MC)이 함유된 물을 입 또는 코로 섭취시 간을 손상시킨다는 보고가 있으며, 최근 해외에서는 MC가 미세먼지처럼 공기 중에 떠다니다 수변에서 생활하는 사람의 호흡기로 들어가 건강 피해를 줄 수 있다는 연구가 속속 나오고 있다. 본 연구는 우리나라 최초의 수질개선용 댐인 영주댐을 연구 대상으로 삼아 수질 모델링을 구축하고 영주댐 운영에 따른 댐 상·하류 조류 변화를 정량적으로 분석하였다. 조류의 강도를 추정하는데 클로로필-a 농도를 사용하였으며, 분석 도구로는 국립환경과학원이 수질예측 및 평가 시 사용하는 EFDC(Environmental Fluid Dynamics Code) 모형을 활용하였다. 대상 구간의 실제 폭, 하상고 분포 등을 고려하여 수표면 격자망을 구현하였으며, 환경부에서 제공하는 수위 및 DO, TN, T-P, 클로로필-a 등을 활용하여 EFDC 모형의 수리 및 수질 재현성 검토를 하였다. 검·보정된 EFDC 모형으로 영주댐의 방류량 변화 및 댐의 개방과 같은 수리학적 요인을 제어하여 특정 지점의 조류 변화를 분석하였다.

• Journal of the Korean GEO-environmental Society
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• v.23 no.9
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• pp.33-40
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• 2022

Sedimentation and pH neutralization has been investigated as preteatment of acid contaminate water. The settling and neutralizing process derive more effective degradation efficiency as the pre-treatment process before the removal process of adsorption, volatile, biodegradation, or oxidation. Settling velocity, uniformity coefficient, coefficient of curvature, and grain size index can define in the sedimentation process for characteristics of the soil. The stainless steel sieve has been used to separate each particle size of the dry soil by assembling in order of 4, 10, 20, 40, 80, 100, and 200 mesh sizes. The soil from Gamcheon Port in Busan drops upper side of the sieve and shakes back and forth to separate each different size of the particle. The 1L of Imhoff cone and 200 mL of the mass cylinder were used as settling tanks to calculate settling velocity. Stokes' equation was used to figure out the average density of dry soil with a value from settling velocity. In the results, the average particle density and lowest settling velocity were 1.93 g/cm³ and 0.11 cm/s, respectively. These values can detect the range of settling points of sediment to prevent chemical accidents. In pH neutralization, the initial pH of 2, 3, 4, and 5 of nitric acid and sulfuric acid are used as an acid solution; 0.1, 0.01, and 0.001 M of sodium hydroxide and calcium hydroxide are used as a base solution. The main goal of this experiment is to figure out the volume percentage of the acid solution becomes pH 7. The concentration of 0.001 M of base solution exceeds all the conditions, 0.01 M exceeds partially, and 0.1 M does not exceed 5 v/v% except pH 2. Calcium hydroxide present less volume than sodium hydroxide at pH neutralization both sulfuric and nitric acid.

• Journal of Chitin and Chitosan
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• v.23 no.4
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• pp.244-255
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• 2018

Natural extract in liquid phase was adjusted to 0, 0.25, 0.5, 1, 2, and 4% concentration to check microbial changes and to measure 4, 8, $12^{\circ}C$ for refrigeration temperature. In the case of grapefruit extract, the microbial safety was maintained at all the concentrations at $4^{\circ}C$ storage, but the antimicrobial activity was maintained at $12^{\circ}C$ storage and at $8^{\circ}C$ and 21 days storage. In the case of grape seed extract, only the 4% of the culture at $8^{\circ}C$ satisfied the requirement of safety of food distribution for the last 21 days, and the safety criterion was satisfied only at 4% concentration at $12^{\circ}C$ for 18 days. Complex Scutellaria baicalensis extract showed the total number of microbial cells treated by concentration. It was confirmed that microbial flow safety was maintained at low temperature ($4^{\circ}C$). However, at $8^{\circ}C$ and $12^{\circ}C$, Exceeded the distribution limit. When polylysine was applied to brown rice cake, it showed activity in all groups except $4^{\circ}C$, but these properties were not observed at $8^{\circ}C$ and $12^{\circ}C$. At a concentration of 0.5% or more of chitosan, the growth of the microorganism is suppressed by the 21st day very stably, and a similar tendency is observed at 8 and $12^{\circ}C$, so that it may be an antimicrobial material that inhibits microorganisms. At the first day, the distribution standards for general bacterial counts were exceeded.Ethyl-pyruvate showed that microorganism safety was maintained at $4^{\circ}C$ and 1% concentration, and food safety was stable even at 2 or 4%. Glycine showed very good and stable distribution stability at $4^{\circ}C$. However, at $8^{\circ}C$ and $12^{\circ}C$, the shelf life of 14 days could not be maintained as with the addition of other antimicrobial active substances.

• Journal of the Korean Society of Food Science and Nutrition
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• v.37 no.3
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• pp.309-316
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• 2008

This study was carried out to examine the effects of vitamin E on chronic gastric ulcer induced by alcohol treatment in rats. Chronic gastric ulcer model was established by oral administration of 70% ethanol at one time and supply of 15% ethanol for additional 7 days. Male Sprague-Dawley rats, approximately 200 g, were fasted for 24 hours and orally gavaged with 1 mL of 70% ethanol for the induction of acute ulcer. A supply of 15% ethanol dissolved in distilled water for 7 days were followed to maintain chronic gastric ulcer. Acute ulcer group was sacrificed at 3 hours after oral administration of 1 mL of 70% ethanol. Chronic groups were divided into three groups according to vitamin E levels; low-vitamin E (LVE, 0 mg/mL oil/day), normalvitamin E (NVE, 1 mg/mL oil/day) and high-vitamin E (HVE, 10 mg/mL oil/day). These groups were fed vitamin E free diets which were made of vitamin E free vitamin mix followed AIN-93M pattern for 7 days. Histological findings of congestion, hemorrhage and necrosis in gastric tissue were shown severely in acute ulcer group and LVE group of chronic ulcer groups. The concentration of gastrin in serum was significantly higher in LVE group. The content of histamine in stomach was lower in acute ulcer group but there was no significant difference among the chronic groups regardless of vitamin E levels. Content of malondialdehyde (MDA) in gastric tissue was higher in HVE group and activities of antioxidant enzyme, glutathione peroxidase (GPx) and catalase, were lower in HVE group. Myeloperoxidase (MPO) activities as a marker of neutrophils infiltration was significantly higher in LVE group. These results suggested that vitamin E supplementation has positive effects on healing of alcohol-induced chronic gastric ulcer through alleviation of gastric tissue injuries and reduction of the MPO activity in gastric tissue and gastrin in serum.

• The Korean Journal of Malacology
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• v.31 no.2
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• pp.129-136
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• 2015

To introduce an oyster rack culture in tidal flat of Wando-gun, Korea, we investigated sanitary conditions from 2012 April to 2013 March in oyster growing waters and adjacent area in Wando. Average seawater temperature and salinity ranged $8.6-28.0^{\circ}C$ and 26.2-33.6 psu, respectively. The coliform group and fecal coliform of seawater ranged < 1.8-13.0 MPN/100 mL each. Only one of 60 samples was exceeded in the European criteria of fecal coliform. Influence of adjunct basin's pollution load on cultural waters was negligible, which half radius of dilution was not above 300 m. According to our observation, however, landing of oyster should be banned for at least 5 days after the heavy rainfall. Our findings meet the sanitary seawater criteria for domestic use and export of shellfish and classified as 'Class A' in European Community regulations for bivalve culture.

• Journal of Animal Science and Technology
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• v.44 no.2
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• pp.221-232
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• 2002

This study was conducted to investigate the effects of deficiency of essential amino acid in diet on feed intake and concentrations of free amino acid in plasma and brain(prepyriform cortex, PPC), and thereby to know the brain area engaged in the mechanism of feed intake regulation. In all trials, experimental diets were formulated with pure amino acid mixture to level of 15% nitrogen. Rats were trained to eat a single meal for 6 hours daily(meal feeding, 17:00-21:00). Feed intake and body weight were measured hourly on and after 7th day of feeding. In Exp. 1, feed intake and body weight were measured every hour, and the free amino acid concentrations of plasma and PPC were analysed at 0, 1, 2, 3 and 6 h on the 11th day of feeding. In Exp. 2, the complete diet was replaced with lysine devoid diet at the 11th day, and feed intake, body weight and free amino acid concentrations in plasma and PPC were samely measured on Exp. 1. In Exp. 1, feed intake on complete diet was self-sufficiented to daily feed intake level(15g/day) from the 7th day. Free amino acid concentrations of plasma and PPC at the 11th day were plateau at 1 hour after feeding. In Exp. 2, feed intake was quickly reduced by the diet replacement(P$<$0.05), and the free lysine concentration of plasma and PPC was also significantly decreased at 2 hour after feeding. However, cumulative feed intake was significantly decreased at 4 hour after feeding. These results may indicate that the concentrations of free lysine in plasma and PPC, under the condition of devoided lysine in diet, were more quickly droped than the reduction of feed intake rate. Hence, it is expected that PPC in brain might be a part of response area for limited amino acid.