• Korea-Australia Rheology Journal
• /
• 제20권3호
• /
• pp.109-116
• /
• 2008

The effect of intermolecular aggregation induced by hydrophobic and electrostatic interactions on shear and elongational flow properties of aqueous acrylic thickener solutions is discussed. Complex shear modulus is determined at frequencies up to $10^4$ rad/s employing oscillatory squeeze flow. Extensional flow behavior is characterized using Capillary Break-up Extensional Rheometry. Aqueous solutions of poly(acrylic acid)(PAA)/poly(vinylpyrrolidone-co-vinylimidazole) (PVP-VI) mixtures exhibit unusual rheological properties described here for the first time. Zero-shear viscosity of the mixtures increases with decreasing pH and can exceed that of the pure polymers in solution by more than two orders of magnitude. This is attributed to the formation of complexes induced by electrostatic interactions in the pH range, where both polymers are oppositely charged. PAA/PVP-VI mixtures are compared to the commercial thickener Sterocoll FD (BASF SE), which is a statistical co-polymer including (meth) acrylic acid and ethylacrylate (EA) forming aggregates in solution due to "sticky" contacts among hydrophobic EA-sequences. PAA/PVP-VI complexes are less compact and more deformable than the hydrophobic Sterocoll FD aggregates. Solutions of PAA/PVP-VI exhibit a higher zero-shear viscosity even at lower molecular weight of the aggregates, but are strongly shear-thinning in contrast to the weakly shear-thinning solutions of Sterocoll FD. The higher ratio of characteristic relaxation times in shear and elongation determined for PAA/PVP-VI compared to Sterocoll FD solutions reflects, that the charge-induced complexes provide a much stronger resistance to extensional flow than the aggregates formed by hydrophobic interactions. This is most likely due to a break-up of the latter in extensional flow, while there is no evidence for a break-up of complexes for PAA/PVP-VI mixtures. These flexible aggregates are more suitable for the stabilization of thin filaments in extensional flows.

• 대한수학교육학회지:학교수학
• /
• 제11권3호
• /
• pp.497-511
• /
• 2009

본 연구는 서울시에 위치한 초등학교 3학년 아동 53명을 대상으로 도식기반 전략 프로그램으로 수학 문장제를 교수함에 있어 중재재료 투입방법(병렬, 순차)에 따른 수행결과를 처치집단, 문제유형(결합, 변화, 비교), 회기별(사전검사, 사후검사 3회)로 알아보고자 하였다. 사전, 사후검사 문항은 곱하기와 나누기 연산을 필요로 하는 결합, 변화, 비교 문제로 각 3문제씩 9문제로 구성되었으며 각 회기가 끝난 다음날 바로 사후검사로 수행 정도를 측정하였다. 본 연구결과에 따르면 문장제 유형별 수행이 교수재료 투입시기에 큰 영향을 받지 않았으나 문제구조가 유사한 결합형 문제와 변화형 문제인 경우 나중에 교수한 변화문제의 도식이 결합문제의 도식 생성에 혼란을 주어 결합문제의 수행이 떨어지는 결과가 나타났다.

• 대한수의학회지
• /
• 제35권1호
• /
• pp.1-9
• /
• 1995

The development of omasum in fetuses between 60, 90, 120 days of gestation and neonates of Korean native goats was investigated by fight; scanning electron microscopy. The results were summarized as follows : 1. In the 60-day-old fetuses, the stomach was developed and differentiated into four compartments of rumen, reticulum, omasum, and abomasum. The mucosa of the omasum was thrown into folds which appeared to be three or four different orders of large, medium, small, and smallest laminae. 2. In the 90-day-old fetuses, the omasal laminae had increased greatly in length and cores of omasal laminae were invaginated laterally. 3. In the 120-day-old fetuses, the wall of the omasal laminae had increased in length and the lamina epithelialisis had slightly increased in thickness. The lateral invaginations at the dark zone had increased in length and depth. The tunica muscularis increased only slightly in thickness particularly within its inner circular layer. 4. In the neonate, the muscularis and the omasal laminae had increased in thickness. The lateral invaginations of the dark zone were observed in the first, second and third order of omasal laminae. 5. Scanning electron microscopic studies : In the 90-day-old fetuses, numerous microvilli and microridges were observed on the luminar surface of the omasal mucosa. The omasal papillae were already formed at 120 days of gestation. In the I20-day-old fetuses omasal papillae liked nipple shape. In the neonate, the omasal papillae liked the thumb.

• 한국응용곤충학회지
• /
• 제29권1호
• /
• pp.14-19
• /
• 1990

부산, 경남, 경북, 전남, 전북 22개 지역 19수종 238본의 고사목에서 1989년 4월부터 9월까지 선충류와 곤충류를 조사한 결과, 소나무 재선충은 부산지역에서만 검출되었으며, 어리소나무 재선충은 진주와 진해에서 분포가 확인되었다. 고사목에서 분리.동정된 선충류는 9속 13종이었으며 6속은 미동정되었다. 동정된 선충 중 Diplogasteroides dimidius, Rhabdontolaimus adephagus, R.janae, Mikoletzkya diluta, M. ruminis, m. langcauda, Parasitorhabditis hylurgi, Panagrolaimus concolor, Panagrodontus dentatus, Prothallonema intermedium, Macrolaimus canadensis는 우리나라 미기록종이다. 한편, 고산목에서 채집된 곤충은 5목 9과 25속 27종이었는데 딱정벌레목이 3과 19속 22종으로 가장 많았다. 그중 나무종이 10속 12종으로 빈번히 채집되었으며, Hypothenemus eruditus가 꽃싸리, 싸리, 조록싸리, 만리화, 닥나무에서 채집되어 새 기주로 추가되었다. 소나무 재선충의 매개충인 솔수염하늘소는 복부에서의 선충 검출수가 가장 많았으며, 성충 한마리당 선충 보유수는 최대 127,535마리, 최소 2,616마리, 정균 42,817마리였다.

• 한국환경보건학회:학술대회논문집
• /
• 한국환경보건학회 2004년도 International Conference Global Environmental Problems and their Health Consequences
• /
• pp.173-177
• /
• 2004

The acute toxicities of two major anti-pathogenic veterinary medicines, i.e., ciprofloxacin and enrofloxacin, and six benzimidazole anthelmintics, i.e., albendazole, thiabendazole, flubendazole, febantel, fenbendazole, and oxfendazole, were evaluated with a marine bacterium, Vibrio fischeri, and invertebrate Daphnia magna. These veterinary medical products have been widely used for farm animals, but their impact on aquatic fauna has seldom been investigated. In general, daphnids responded as much as 3 orders of magnitude more sensitively to the tested pharmaceuticals than the microbes. For Daphnia, the most toxic product among the tested anthelmintics was fenbendazole, followed by flubendazole > albendazole ${\approx}$ febantel > thiabendazole > oxfendazole. Daphnids' EC50 values obtained from 48 to 96 hrs of fenbendazole exposure ranged from 2.7 to 6.3 ug/L. The mixture toxicity of the test pharmaceuticals was generally additive in nature and was well predicted by a concentration addition model. Using the predicted no effect concentrations (PNECs) of the benzimidazole derivatives estimated from this study, and predicted environmental concentrations (PECs) of these pharmaceuticals, the risk quotients of each anthelmintics were calculated. Most of the test anthelmintic compounds resulted in risk quotients greater than 1. Especially, risk quotient for fenbendazole was 2,791, which strongly indicates this compound might cause severe ecological consequences, should no future action be taken. This study is the first report on the aquatic toxicities and potential ecological risk of major anthelmintic and antimicrobial veterinary products in Korea. The result of this study provides information necessary for conducting more detailed ecological risk assessment of pharmaceutical products in ambient water and guiding proper management decision.

• 혜화의학회지
• /
• 제10권1호
• /
• pp.157-166
• /
• 2001

Oryoungsan which first recorded in Sanghanron, the clinical medical book consists of treating acute febrile disease according to its change, is one of the frequently used oriental medicines. these days, it has been prescribed in symptoms accompanied by edema mostly. therefore it is easy to consider it as a type of diuretics. In Sanghanron it was originally used in the symptoms of perspiration, decreased urine volume, thirsty, flatulence. these symptoms indicate loss of body fluid and the prescription which orders "taking warm water sufficiently" supports this. On this background, it is supposed that Oryoungsan treats dehydration after providing water and electrolytes. To consider that herbal medicines consisted of Oryoungsan make electrolytes go out of the body, The healing mechanism of dehydration doesn't meet this. Because Oryoungsan was used in condition of fever or in similar condition, it is more resonable to understand that restoration of increasing blood flow to the subcutaneous venous plexus regulating body temperature in febrile condition into body circulation, resulting into maintaining main blood volume and into treating decreased urine volume and thirsty is Oryoungsan's function in the dehydration or febrile condition. That is, symptoms are decreased or disappeared through restoring unbalance of internal body fluid. The other target is pain controls, especially chronic headache, facial pain and trigeminal neuralgia. it is suggested that the function of pain control of Oryoungsan is related to 5-HT(5-hydroxytrypamine), nerve transmitter in the endogenous analgesic system. Moreover it is also suggested that Oryoungsan is relate to 5-HT, considering the fact that gastroparesis, a symptom of cyclic vomiting syndrome treated with 5-HT1D receptor agonist is similar to the 'bi', symptoms appeared in the Oryoungsan-related disease.

• 한국물환경학회지
• /
• 제34권5호
• /
• pp.503-513
• /
• 2018

Freshwater cyanobacterial genus Dolichospermum is one of the most commonly spotted types of phytoplankton, whereas a limited number of studies on morphology of Dolichospermum spp. have been performed in South Korea. The purpose of this study is to investigate the succession pattern of cyanobacteria after weir construction, as well as morphological characteristics of Dolichospermum spp. from natural samples collected in the weir regions of Nakdong River. A total of 31 cyanobacterial taxa observed in this study were classified as belonging to 15 genera, 5 families, and 3 orders. Among them, morphological characteristics in the four species were classified into genus Dolichospermum, for most of the planktic former members of the genus Anabaena, were observed through light microscopy. Water bloom frequently occurred in the middle region of Nakdong River, the maximum number of cyanobacterial species appeared in the lower region of Nakdong River. The appearance of order Chrooccocales was only observed during summer when population density of Microcystis aeruginosa reached an annual peak. In contrast, filamentous cyanobacteria was observed throughout the whole year, even if when water temperature was lower than $5^{\circ}C$. It implied that the low-temperature-adapted filamentous cyanobacteria can grow in a range of water temperatures. Coil diameter of D. crassum from natural samples was $75{\sim}140{\mu}m$ ($ave.=91.3{\mu}m$; n = 94), slightly larger than those reported by previous studies. Dolichospemum smithii ($Kom{\grave{a}}rek$) Wacklin et al. 2009, was described for the first time in Nakdong River.

• 한국경영과학회:학술대회논문집
• /
• 대한산업공학회/한국경영과학회 2002년도 춘계공동학술대회
• /
• pp.449-455
• /
• 2002

This paper considers that advanced planning and scheduling (APS) in manufacturing and the efficient purchasing where each customer order has its due date and multi-suppliers exit We present a Make-To­Order Supply Chan (MTOSC) model of efficient purchasing process from multi-suppliers and APS with outsourcing in a supply chain, which requires the absolute due date and minimized total cost. Our research has included two states. One is for efficient purchasing from suppliers: (a) selection of suppliers for required parts; (b) optimum part lead­time of selected suppliers. Supplier selection process has received considerable attention in the business­management literature. Determining suitable suppliers in the supply chain has become a key strategic consideration. However, the nature of these decisions usually is complex and unstructured. These influence factors can be divided into quantitative and qualitative factors. In the first level, linguistic values are used to assess the ratings for the qualitative factors such as profitability, relationship closeness and quality. In the second level a MTOSC model determines the solutions (supplier selection and order quantity) by considering quantitative factors such as part unit price, supplier's lead-time, and storage cost, etc. The other is for APS: (a) selection of the best machine for each operation; (b) deciding sequence of operations; (c) picking out the operations to be outsourcing; and (d) minimizing makespan under the due date of each customer's order. To solve the model, a genetic algorithm (GA)-based heuristic approach is developed. From the numerical experiments, GA­based approach could efficiently solve the proposed model, and show the best process plan and schedule for all customers' orders.

• 한국응용곤충학회지
• /
• 제31권2호
• /
• pp.170-173
• /
• 1992

단자엽식물아강의 잡초가해 곤충을 조사하기 위하여 1991년 5월부터 10월까지 전국의 각도를 전자형으로 나누어 교차지점인 9개지역을 중심으로 각도에서 무작위로 실시한 결과 잡초로는 벼목에서 14속 14종이 채집되었으며 분질배유목에서 1종, 백합목에서 1종등 17속 17종이 채집되었다. 이들을 가해하는 곤충으로는 5목 13과 27속 36종이 채집되었는데 메뚜기류와 노린재류 및 풍뎅이와 잎벌레가 빈번하게 채집되었고 5종은 미동정 되었다. 그중 닭의장풀에서 노란배남색잎벌레의 가해능력이 우수하였고 강아지풀에서 Oulema dilutipes 잎벌레가 처음으로 채집되었다. 그리고 골프장의 닭의장풀에서 채집된 다색풍뎅이는 가해능력은 우수하였으나 잔디와 수목해충으로 이들에게 피해를 줄 수 있는 가능성이 높아 바람직하지못하였다.

• 한국응용곤충학회지
• /
• 제46권3호
• /
• pp.375-383
• /
• 2007

곤충의 채집방법, 횟수 및 시기와 채집된 곤충의 종류 및 개체수에 대한 상관관계를 조사하기 위하여 충북대학교 내 4곳을 선정, 일 년간 봄부터 가을까지 매 2주마다 채집을 실시, 총 16회 조사를 하였다. 각 장소마다 light trap, net sweeping, pitfall trap, window trap의 4가지 채집방법을 병행 실시하여 결과를 비교분석하였다. 모두 14목 672종이 조사되었으며, 전체 종수의 75%인 501종이 채집된 유아등 채집(light trap)방법이 18% 또는 그 이하의 종수를 기록한 타 채집방법들에 비해 보다 효과적인 것으로 나타났다. 또한 각 채집시기에서 채집된 종이 2주 후의 채집에서 다시 채집되는 비율이 평균 30% 정도 밖에 되지 않았다. 결과적으로 곤충다양성 조사에 있어서 보다 의미 있는 결과를 확보하기 위해서는 다양한 채집방법과 함께 채집의 빈도(sampling window)를 높이는 것이 특히 중요한 것으로 나타났다.