Cavitation can occur in pipes when liquid is moving at high velocity, especially at pittings where the smooth bore of the pipe is interrupted. The effect is usually to produce pitting on the downstream side of the turbulence. However, stress corrosion cracking behavior under cavitation erosion-corrosion was neatly unknown. In this study, therefore, some were investigated of stress corrosion cracking behavior, others were stress corrosion cracking behavior under cavitation erosion-corrosion of water injection. And datas obtained as the results of experiment were compared between the two. Mainresult obtained are as follows: 1) Stress corrosion cracking growth rate of heat affected zone under cavitation erosion-corrosion becomes most rapid, and stress intensity factor K1becomes most high. 2) Stress corrosion cracking growth mechanism by cavitation erosion-corrosion is judgement on the strength of the film rupture model and the tunnel model. 3) The range of potential as passivation of heat affected zone is less noble than that of base metal, and that value is smaller. 4) Corrosion potential under cavitation erosion-corrosion in loaded stress is less noble than that of stress corrosion, and corrosion current density is higher.

The effect of fluid flow on corrosion and erosion-corrosion of metal is a well-recognized phenomenon in pipelines and machinery equipment, and so on. Not only are fluid hydrodynamics important, but also the corrosiveness of the process or production stream affects the corrosion system. Recent research demonstrates that it is possible to erosion-corrosion(E/C) phenomena in terms of hydrodynamics, electrochemical corrosion kinetics and film growth/removal phenomena. Stress corrosion cracking behavior under cavitation erosion-corrosion of mild steel(SS41) was investigated of base metal and weldment under loaded stress. Main result obtained are as follows : 1) The cavitation erosion sensitivity of base metal affected weight loss is more susceptive than heat affected zone, 2) The corrosion sensitivity affected weight loss of welding heat cycle is less susceptive on stress corrosion under cavitation erosion-corrosion than stress corrosion.

수분(水分) 스트레스에 의한 식물체(植物體)의 방어기구(防禦機構)와 관련(關聯)된 superoxide dismutase와 catalase의 활성도(活性度) 변화(變化)를 조사(調査)한 결과(結果)는 다음과 같다. 수분(水分) 스트레스(drought, flooding) 처리시(處理時) 큰올콩과 은하콩 모두 수분(水分) 함량(含量)과 가용성(可溶性) 단백질(蛋白質) 함량(含量)이 감소(減少)하여 말성숙(末成熟) 노화(老化)를 나타내었다. 가시적(可視的)인 피해(被害)는 drought 처리시(處理時)가 flooding 처리(處理)에 비(比)해 크게 나타났고 큰올콩이 은하콩에 비(比)해 크게 나타났다. superoxide dismutase의 활성(活性)은 drought처리시(處理時) 2일(日)째에 급격(急激)한 감소(減少)를 보이다가 회복(回復)되고 다시 감소(減少)하는 경향(傾向)을 보였으며 flooding처리시(處理時)는 처리기간(處理期間)에 따라 점차(漸次) 감소(減少)하였고 큰올콩의 감소정도(減少程度)가 더 크게 나타났다. catalase의 활성(活性)은 drought처리시(處理時)는 감소(減少)하는 경향(傾向)이었으나 flooding처리시(處理時) 2일(日)째에 급격(急激)한 감소(減少)를 나타낸 후 일정(一定)하게 유지(維持)되는 경향(傾向)을 보였다. 수분(水分)스트레스 처리후(處理後) 3일간(日間)의 회복기(回復期)를 주었을 때 두 효소(酵素)의 활성(活性)은 점차(漸次) 회복(回復)되었다.

가압 경수로형 원전에 사용되는 Alloy 600 증기발생기 전열관재료의 입계응력부식균열 거동에 미치는 냉간변형의 영향을 1차 냉각수 모사조건에서 정속인장시험방법으로 조사하였다. 인장 냉간변형은 응력부식균열을 크게 가속화 시키지는 않았으며 변형량이 25%이상인 경우에는 응력부식균열이 발생하지 않았다. 이 현상은 냉간 변형량 및 형태에 따른 미소변형 및 응력의 불균질성에 영향을 받는 것으로 사려되며 응력의 크기는 직접적인 영향을 주지 않는 것으로 보인다. 국부적인 큰 응력구배가 존재하는 경우 균열의생성 및 성장이 현저히 가속화되었는데 이는 원전 1차측 응력부식균열 기구가 응력구배에 의존하는 과정과 연관되어 있다는 증거이다. Hump 시편을 이용한 정속인장시험방법은 짧은 실험기간내에 원전 1차측 응력부식균열 특성을 평가할 수 있는 방법이었다.

본 연구는 스트레스에 의해 발생하는 위궤양에 대한 Opuntia dillenii Haw.(선인장)의 효과를 관찰하고자 시행되었다. 실험동물로는 Sprague-Dawley계 수컷 흰쥐 48마리를 사용하였며, 대조군(CO)과 3개의 투여군(E-1, E-2, E-3)으로 나누어 1996년 7월 29일부 1996년 8월 25일까지 4주간 실험을 수행하였다. Opuntia dillenii Saw.(선인장)는 1일 1회 경구투여하였으며, 각각 30 mg/kg BW(E-1) 및 120 Mg/kg BW(E-3)의 농도를 투여하였다. 결과느 s다음과 같다. 1. 체육은 전 군에 걸쳐서 고르게 증가되었으며, 특히 실험시작 후 13일째 체중증가량은 대조군에 비하여 Opuntia dillenii Haw.(선인장)를 투여한 실험군 실험군에서 유의한 차이는 관찰되지 않았다. 4. Alcian bule staining을 통한 위점액량 산출 결과 Opuntia dillenii Haw.(선인장)를 투여한 실험군이 대조군에 비해 전 농도에서 점액량이 높게 나타났으며, 실험군 E-1군은 유의하게 높았고(p<0.05), 실험군 E-2의 경우 그 증가가 현저하였다(p<0.01). 이로서 Opuntia dillenii Haw.(선인장)가 위의 점액생성을 촉진시키거나 위에 보호막을 형성함으로서 위궤양 발생저하에 기여하는 것으로 보여진다. 5. shear rate 11.25, 45.0, 90.0 및 225.0 sec^(-1)에서 전혈점도 및 혈장점도를 측정한 결과 모든 shear rate에서 C군>E-3군>E-1군>E-2군의 경향성을 보였다. E-1(30 mg/kg BW)군의 전혈점도는 대조군에 비하여 shear rate 11.25, 45.0 sec^(-1)에서는 매우 유의하게 감소하였고(p<0.01), shear rate 90.0, 225.0 sec^(-1)에서도 유의하게 감소되었다(p<0.05). E-2(60 mg/kg BW)군의 전혈점도는 대조군에 비하여 매우 유의하게 감소하였고(p<0.01). E-3(120 mg/kg BW)군의 전혈점도는 대조군에 비하여 shear rate 11.25 sec^(-1)에서 매우 유의하게 감소되었고 (p<0.01), shear rate 45.0, 225.0 sec^(-1)에서도 유의하게 감소되었다(p<0.5). 동일한 shear rate에서의 혈장점도는, E-1(30 mg/kg BW)군은 대조군에 비해서 shear rate 90.0 sec^(-1)에서 유의하게 감소되었다(p<0.05). E-2(60 mg/kg BW)군의 혈장점도는 대조군에 비해 shear rate 90.0, 225.0 sec^(-1)에서 유의하게 감소되었다(p<0.05). E-3(120 mg/kg BW)군은 대조군에 비해 전 shear rate에서 모두 감소하였으나 유의한 차이는 보이지 않았다. 이러한 결과로부터 Opuntia dillenii Haw.(선인장)가 스트레스하에서 발생하는 위의 미세혈관 협류흐름장애를 개선시켜 위게양 발생저하에 기여하는 것으로 보여진다. 6. 전 실험군의 위를 조사한 결과 출혈을 동바한 궤양이 형성되었음을 관찰할 수 있었다. Opuntia dillenii Haw.(선인장)투여군에서는 대조군에 비해서 궤양의 면적과 깊이가 다소 적은 경향을 나타내었다. 7. 위조직에 대한 병리조직학적 검사를 시행한 결과 Opuntia dillenii Haw.(선인장)을 투여한 실험군에 비하여 대조군의 궤양이 매우 심함을 관찰할 수 있었고, E-2군의 경우 궤양이 경미한 정도였다. 8. 위궤양의 지표로 사용한 pH, 위점액량, 전혈점도, 혈장점도, 조직병리학적소견 등을 종합한 결과, Opuntia dillenii Haw.(선인장)를 투여한 실험군이 대조군에 비해서 항궤양효과가 있는 것으로 나타났으며, 치료양의 2배를 투여한 E-2(60 mg/kg BW)군에서 효과가 가장 뛰어났다.

4종(種)의 상치를 공시작물(供試作物)로 하여 수분(水分) 스트레스에 노출(露出)을 시켰을 때 총(總) 단백질(蛋白質)의 함량(含量)은 Flooding 처리시 그 감소율(減少率)이 더 크게 나타났으며 감소율(減少率)은 JCM이 가장 컸고, DCM이 가장 작았으며 품종간(品種間) 각 처리별(處理別) 차이(差異)가 크게나타났다. 총(總) 지질(脂質)의 함량(含量)은 감소율(減少率)이 CCM이 가장 컸고 JCM, DCM, DJM순(順)으로 감소(減少)하였다. 항산화효소(抗酸化酵素)인 Superoxide Dismutase(SOD)는 Catalase, Ascorbate Peroxidase의 활성도(活性度)는 전체적으로 감소(減少)하였으며 그 감소율(減少率)은 Catalase의 경우 처리별 JCM이 가장 크게 나타났고 DCM, DJM에서는 Flooding 처리시 효소의 활성도 변화가 더 크게 나타났다. Calatase의 활성도(活性度) 변화(變化)가 Ascorbate peroxidase의 활성도(活性度) 보다 감소율(減少率)이 더 크게 나타나 이는 Catalase가 Ascorbate peroxidase 보다 과산화수소(過酸化水素)와 더 직접적(直接的)으로 반응(反應)을 함을 나타낸다. Drought 처리기간별(處理期間別) 효소(酵素)의 활성도(活性度)는 생육시간(生育時間)이 길어질수록 감소(減少)하는 경향(傾向)이었으며 Catalase의 활성도(活性度)가 4일째 이후 가장 급격하게 감소(減少)하였다.

Recently with the rapid development in the industries such as an iron mill and chemical plants, these are enlarged by the use of the piping. This piping was encountered the stress corrosion cracking(SCC) because of stress by water pressure and residual stress of welding etc. under industrial water. In this paper, the behaviour of stress corrosion cracking on the weld zone of steel pipe piping water(SPPW) were investigated according to pre-heat before welding in natural seawater(specific resistance : 25Ω-cm). The main results obtained are as follows :1) The stress corrosion cracking for SPPW and SB 41 is most ready to propagate in heat affected zone of weldment. 2) The SCC sensitivity of SPPW on weldment is more susceptible than that of SB 41. 3) The stress corrosion cracking growth of heat affected zone is delayed by the preheat and dry of base metal and electrode before welding.

1. 배양액의 EC(mS/cm)와 배양액의 수분포텐셜은 직선적인 관계가 있고, EC의 증가는 배양액의 수분포텐셜 저하로 나타났으며 이에 따라 상위엽의 수분포텐셜이나 침투포텐셜이 변화하는 경향을 보였다. 2. 물리화학, 열역학적인 지표가 되는 수분포텐셜(Φw)은 배양액 뿐만 아니라 식물의 근, 경, 엽 및 과실에서의 수분 상태를 동일 단위로 나타내는 것으로 식물의 생장을 제어할 때 유일한 지표인 것으로 나타났다. 3. 배양액의 수분포텐셜 저하에 따라 상위엽의 수분포텐셜이나 침투포텐셜이 저하하는 경향을 보였다. 4. 배지내 Cu 농도가 5μm이상으로 되면 생육, 지상부의 생체중, 지하부의 건물중, 엽록소 함유율이 동시에 급격히 저하하는 경향을 보였다. 5. 배지내 Cu 농도의 증가에 따라서 생장율의 저하가 나타났으며 생장율의 저하에 따라 상위엽의 수분포텐셜이 저하하는 경향을 보였다. 팽압은 처리에 관계없이 거의 일정하게 나타나 팽압과 배지내 배양액의 Cu 농도 스트레스간에는 직접적으로 관계가 없는 것으로 나타났다. 수분포텐셜(ψw)은 식물신장, 세포신장을 수적으로 표현하는 것이 가능하다. 수원이 되는 용액이나 배지, 식물체를 동일 단위(㎫)로 관찰하는 것이 가능해 식물체의 수분생리적 비교 검사를 위한 유효한 방법으로 생각되었다.

수분장애조건에서 오차드그라스(cv. Potomac) 종자의 발아력을 향상시키기 위하여 Polyethylene glycol 6,000(PEG) 및 생장조절제(GA, Kinetin, NAA)를 종자에 전처리하여 0 bar와 -5 bar의 두 수분조건하에서 17일간 발아양상을 비교, 검토하였는데 그 결과는 다음과 같다. 1. 전처리를 하지 않은 종자는 수분 삼투압 -5bar 조건에서 대조구(0 bar)에 비해 총 발아율은 감소되었으며 평균발아 소요일수와 발아

수분 장애시 목초 발아 특성을 검토하기 위하여, 삼투압 0, -5 bar 두 수준에서 tall fescue, orchardgrass, Kentucky bluegrass 및 alfalfa의 총 발아율, 발아속도계수를 구하였으며, 누적 발아율의 경시적인 변화를 logistic 및 Weibull 함수를 이용하여 비선형회귀 잔차에 의하여 함수간 비교를 하였고, 각 함수로부터 추정된 계수를 조사 하였던바 다음과 같은 결과를 얻었다. 1. 삼투압 수준 -5 bar

This study aimed to analyze the growth and physical responsees of Dracaena braunii in response salt accumulation in ornamental water culture and to examine the effect of activated carbon on this growth response. The experiment was conducted in a plant growth chamber and the indoor environmental conditions of the chamber were set at 23 ± 1℃ temperature, 70 ± 3% humidity, and 1,000 lux brightness. The observation of the growth response of plants in the presence of activated carbon showed that the pH with activated carbon maintained sub-acidic to neutral (6.27∼7.32) conditions and showed decreased electric conductivity in the media. As the treatment with added activated carbon showed good growth and physical responses, this indicated that absorption effect of activated carbon had a positive influence on the growth of plants. However, as the absorption effect of activated carbon may decrease over time and the use of high concentrations of activated carbon might cause nutrition shortage, various concentration of activated carbon and their absorption effects need to be investigated in the future.

Background : Gastrodia elata (GE) is a perennial herb that belongs to the orchidaceae and is used as a medicinal or food material. Known pharmacological agents include gastrodin and 4-hydroxybenzyl alcohol. It is used as medicinal herb that is traditionally used for headache, migraine, dizziness, epilepsy and infant seizures. It is used for medicinal herbs such as sedation, hypnosis, epilepsy treatment, anticonvulsant, antidepressant, neuroprotection, antipsychotic, anticonvulsant, Antioxidant, memory improvement, anti-aging, antiviral, anti-tumor. The purpose of this study was to find the extraction method with the highest oxidative stress inhibition and to optimize the pharmacological effect of the extract. Methods and Results : GE was freeze-dried to obtain 5 g, and then extracted into 50 ㎖ of water. Extraction temperature was 0, 30, 60 and 90℃ for 20, 40, 60 and 120 min, respectively. After centrifugation, the mixture was filtered through a 0.45 ㎛ filter. ABTS scavenging ability, DPPH scavenging ability, total phenol content, neuronal cell line (PC12) cytotoxicity, and oxidative stress scavenging activity in neurons were measured by this extract. ABTS scavenging ability, DPPH scavenging ability and total phenol content increased with increasing temperature and extraction time. However, at 60℃ and 90℃ extraction temperature, there was no significant difference. The cytotoxicity of 2 ㎎/㎖ of GE extract was significantly increased in the extract group of 90℃ after 20 hours. Conclusion : From the above results, the water extraction conditions to optimize the pharmacological activity of GE were 120 minutes at 60℃ or less.

The aim of study is to contribute to this knowledge-base by investigating the respiratory function, the metabolic rate and the difference of physiological responses un-der low water temperature (20℃→15℃) stress be-tween diploid and triploid far eastern catfish, Silurus asotus. During the 48 hrs of water temperature stress exposure time, the respiratory frequencies, CO₂ and NH₄+ concentrations of diploid had higher values than those of triploid (p<0.05). However, pH of triploid was higher than those of diploid (p<0.05), and oxygen consumption rate was not different between diploid and triploid (p>0.05). The level of plasma cortisol and plasma glucose of triploid was lower than those of the diploid (p<0.05). However, in case of lactic acid, there were not significant between triploid and diploid (p>0.05). These results suggest that diploid was more sensitive for low water temperature stress response than triploid in this species.

Background : Oxidative stress and inflammatory response are important features of the brain pathology of Alzheimer's disease. Therefore, the purpose of this study was to the antioxidant activity and biochemical characterization of safflower seed. Moreover, we investigated the impact of Safflower seed on scopolamine-induced memory impairment in mice. Methods and Results : First, in order to determine active ingredient contents of safflower seed extract, we were carried out total phenol content and total flavonoid content analyses. As a result, dried safflower seed were found to contain 35.4 ± 0.4 ㎎·GAE/g dry weight and 45.3 ± 7.5 ㎎·NE/g dry weight in boiling water extraction. Also, the major compounds of safflower seed from HPLC analysis were identified as serotonin and serotonin derivatives [N- (p-coumaroyl)serotonin and N-feruloylserotonin]. In addition, the antioxidant activity of safflower seed showed IC50 values of 331.4 and 168.2, respectively, against DPPH and ABTS in vitro. Finally, with regard to the memory improvement activity, the administration of Safflower seed extract significantly restored memory impairments induced by scopolamine in the behavior tests such as novel object recognition and Morris water maze test. Conclusion : The results of our study suggest that the safflower seed extract possess potent memory improvement activity and are also a good source of natural antioxidants. Further study is needed to identify the mechanism responsible for their memory improvement activity.

Background: This study aimed to investigate out the influence of drought stress on the physiological responses of Dendropanax morbifera seedlings. Methods and Results: Drought stress was induced by discontinuing water supply for 30 days. Under drought stress, photosynthetic activity was significantly reduced with decreasing soil water content (SWC), as revealed by the parameters such as Fv/Fm, maximum photosynthetic rate (PN max), stomatal conductance (gs), stomatal transpiration rate (E), and intercellular CO2 concentration (Ci). However, water use efficiency (WUE) was increased by 2.5 times because of the decrease in gs to reduce transpiration. Particularly, E and gs were remarkably decreased when water was withheld for 21 days at 6.2% of SWC. Dendropanax morbifera leaves showed osmotic adjustment of −0.30MPa at full turgor and −0.13 MPa at zero turgor. In contrast, the maximum bulk modulus of elasticity (Emax) did not change significantly. Thus, Dendropanax morbifera seedlings could tolerate drought stress via osmotic adjustment. Conclusions: Drought avoidance mechanisms of D. morbifera involve reduction in water loss from plants, through the control of stomatal transpiration, and reduction in cellular osmotic potential. Notably photosynthetic activity was remarkably reduced, to approximately 6% of the SWC.

Background : Water uptake and flow across cellular membranes is a fundamental requirement for plant growth and development, and plant water status is important not only for plant growth under favorable conditions but also for ability of a plant to tolerate adverse environmental conditions. Thus identification of plasma membrane water channel genes (aquaporins) in ginseng provides extensive information for functional studies and the development of markers for salinity stress tolerance. Methods and Results : For salinity treatment, the plants were grown for 4 weeks in culture medium gelled with 0.8% Phytoagar, and the old media were replaced with the fresh medium containing NaCl at 0, 50, 100, 200 and 400 mM, respectively. The samples for stress treated and non-stressed plants were collected from 6h to 72h, and frozen immediately into liquid nitrogen. According to the sequence information from the assembled transcripts, four primer pairs were designed from the aquaporin gene regions. In order to determine the pattern of aquaporins expression in ginseng seedlings to salinity stress, we conducted semi-quantitative RT-PCR. Conclusion : A tonoplast intrinsic protein 1 (TIP1)-type aquaporin is not only believed to be essential for plant life, but also to be beneficial for growth under salinity stress. Therefore, a deeper understanding of aquaporin genes in ginseng will be essential for crop improvement, which could help us to understand the molecular genetic basis for the ginseng genetic improvement and also provide the functional genetic resources for selective breeding and transgenic research.

Depression is one of the most common neuropsychiatric disorders and has been associated with the neuroendocrine system and alterations in behavior. Schisandra chinensis Baillon is one of major medicinal plants used as a Korea medicine and food sources, and has been processed in the fields of various food products and medicinal herbs. The chronic mild stress (CMS) protocol is widely used to evoke depressive-like behaviors in laboratory mice or rat. The CMS procedure induced some behavioral changes that are compatible with the common expectations, i.e. 'anhedonic' behavior and can affect corticosterone level. The present study, Schisandra chinensis extract administration by daily gavage from the 3 weeks exhibited an antidepressant-like effect on CMS-induced depression in mice. Schisandra chinensis extract administration at dose of 200mg/kg significantly increased the sucrose consumption, and decreased the immobility durations in forced swim test and tail suspension test. Furthermore the corticosterone level decreased than control group. In conclusion, Schisandra chinensis extract showed antidepressant-like effects on sucrose preference test, forced swimming test and tail suspension test based on CMS model.

Excessive water stress can cause severe damage to sorghum and results in significant yield reduction. The aim of this study is to identify quantitative trait loci (QTL) for excessive water stress in sorghum. As a first step, two out of 21 bmr mutants were selected for their superior agronomic performance and Chlorophyll a fluorescence OJIP transient, and were crossed with an elite Korean cultivar, Hwangkeumchal, to construct mapping populations. One hundred ten out of 236 SSR primers showed polymorphism between two parens, which cover ten chromosomes of sorghum from different published SSR linkage maps of sorghum. Development of recombinant inbred lines from the crosses ‘25M2-0698 x Hwangkeumchal’ and ‘25M2-0404 x Hwangkeumchal’ are in progress using the single seed descendent method for generation acceleration.