• KSCE Journal of Civil and Environmental Engineering Research
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• v.5 no.2
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• pp.91-99
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• 1985

The acceleration levels and durations of seismic inputs for nuclear power plant design are surveyed. Among those inputs, two artificial acceleration time histories with same acceleration level and duration are selected and their characteristics are studied by calculating response spectra and spectrum intensity. The selected time histories which have the duration of 24 sec. satisfy the design response spectra of US Nuclear Regulatory Commission Regulatory Guide 1. 60. One of the selected time histories is improved to have the duration of 15 sec. without significant changes in the other characteristics. A case study of a plane model with 3 lumped masses is done using three time histories, i.e, two selected and one improved time histories. It is found that the improved curve gives almost the same results as the original one and reduces the computer time by about half, whereas two selected time histories give the results with same trend but much different magnitudes each other. It is claimed, however, that the improved time history is not the optimal one, but very economical in practical applications.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.31 no.4
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• pp.426-433
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• 1986

This experiment was carried out to investigate the competitive ability and the interaction of each species in ten mono-and binary-associations of four forage species; orchardgrass, tall fescus, ladino clover, and alfalfa. Each species was grown in intra- and interspecific stands in large pots for one year. And samplings of shoot and root were taken in Spring, Summer, and fall clipping stages. Intra- and interspecific competition was compared and evaluated by expected yield, aggressivity, relative yield total(RYT), compensation index(CI), general combining ability(GCA), and specific combining ability (SCA) with shoot and root dry matter production of each species in monoculture and binary mixture. The forage yield was high in two grass species and the mixture of them, but low in two legume species and the mixture of them. The mixture of tall fescue-ladino clover was evaluated as a productive association with a high PYT(1.05) and a high SCA(0.79), and tall fescue was a more aggressive species in it. Each of grass-grass and legume-legume mixture was less aggressive between two species and lower SCAs than grass-legume mixtures. Especially, orchardgrass was the most agressive species and alfalfa was the least, but tall fescue had the highest GCA and ladino clover had the lowest in shoot competition. Also in root, tall fescue- ladino clover mixture was a good match with a high RYT(l.12) and a high SCA (0.60), and orchardgrass was highest in aggressivity. However, orchardgrass had the highest GCA in root while tall fescue had the highest in shoot.

• 한국방재학회:학술대회논문집
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• 2011.02a
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• pp.159-159
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• 2011

수자원 공급의 시 공간적 편차가 큰 우리나라에서는 수자원을 이용하기 위해서 다수의 댐을 건설하고 있다. 특히, 생활수준의 향상으로 용수 수요가 급증하였기 때문에 용수가 부족한 곳에는 광역상수도 사업 등을 통하여 용수를 공급하고 있다. 댐에서 용수가 공급되기까지의 과정은 일종의 관수로 흐름으로 생각할 수 있다. 관수로 내를 흐르는 유체가 갑자기 정지하게 되면, 유체 운동 에너지의 변화가 유발되고, 그로 인해 관내에 급격한 압력의 상승이 일어나게 된다. 반대로 정지하고 있던 유체가 빠른 속도로 흐르게 되면 압력 감소가 급격하게 발생한다. 이와 같이 유체 운동 상태의 급변에 의한 압력변화와 그에 따른 압력파가 음속의 속도로 상 하류로 전파되는 현상을 수격작용(waterhammer)이라 한다. 통상적으로 수격작용은 밸브 개폐 정도가 갑자기 바뀔 때, 펌프의 급격한 기동이나 정지 시, 터빈 내 전력소요가 갑자기 바뀔 때, 댐 수위의 갑작스런 변화, 펌프 임펠러의 진동, 물 수요의 급격한 변화 등에 의해 발생하며, 수격작용은 유체의 질량과 운동량 때문에 관 벽에 큰 힘을 가하게 되어 정상적인 동수압 보다 몇 배나 큰 압력을 발생시킴으로 관 자체는 물론 펌프, 밸브, 터빈 등 관 시설물을 파손시키거나 진동, 소음 등을 야기시킴으로 대규모 건물, 공장, 발전소 등을 설계할 경우 그에 대한 적절한 대책을 강구하여야 한다. 특히 댐에 연결된 저수지 또는 조정지로부터의 도수로가 압력수로이며 그 길이가 상당히 크면 수차가 급정지했을 경우 수격작용에 의해서 압력터널 내에 과도한 압력상승이 일어난다. 이 압력상승을 방지함과 함께 발전소 부하의 증감에 따라서 수량을 공급하거나, 흡수할 목적으로 압력도수로와 수압관과의 접합부에 자유수면이 있는 수조를 설치한다. 이것을 조압수조(surge tank)라 한다(최영박, 1979). 조압수조에서 부하의 급속한 차단에 의해서 수차로 유입될 수량이 차단되면 도수로 내로 흘러 들어온 물은 관성 때문에 수조 내의 수위를 상승시키고, 수조 수위가 어느 정도 이상으로 되어 저수지 수위 보다 상승하면 수조로의 유입이 정지하고 반대로 수조에서 저수지로 역류하여 수조수위는 하강한다. 즉, 조압수조는 도수로 내에 발생한 과도한 압력을 수조 내 수면의 승강운동을 이용하여 감소시키고 원래의 안정적인 수위로 회복시킨다. 본 연구에서는 수격작용에 대한 댐 안정성을 확보하는 수단 중의 하나인 조압수조에 대해 살펴보았다. 연구대상으로 용담댐을 선정하였다. 용담댐에 대한 기존의 검토결과 수직 갱의 지름이 5m 이상이면 조압수조의 동적안정조건을 만족 시키는 것으로 조사되었다. 댐의 설계홍수위인 EL. 265.5m를 기준으로 조압수조의 안정성을 감소시키지 않는 범위 내에서 조압수조 내 격벽 설치 유 무에 따른 수조의 최적 크기를 산정하였다. 산정결과를 분석한 결과 동일 조건에서 격벽을 설치한 경우가 격벽을 설치하지 않은 경우에 비해서 조압수조의 면적이 약 21% 감소하는 것으로 나타났다.

• Korean Journal of Food Science and Technology
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• v.14 no.2
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• pp.179-183
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• 1982

This experiment was carried out to clarify the optimal concentrations of growth regulators for callus induction and the condition of callus culture of leaf tissue taken from Stevia rebaudiana Bertoni. The content of stevioside, sweetening component, in leaf-derived callus of stevia was also investigated. It was shown that the optimal concentrations of benzyladenine (BA) and ${\alpha}-naphthalene$acetic acid (NAA) for callus induction were $10^{-6}M$ and $10^{-5}M$, respectively. Reculture of these calli in media (Linsmaier and Skoog) supplemented with BA $10^{-6}M$ and NAA $10^{-5}M$ resulted in profuse calli 15 to 20 days after incubation. When sweetening components produced by callus were extracted and identified by TLC, stevioside appeared to have Rf value 0.50 in TLC which was exactly same as standard stevioside. Stevioside content obtained by TLC-FID analyzer was 260mg per 100g on the basis of dry weight.

• Journal of Environmental Policy
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• v.8 no.2
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• pp.1-23
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• 2009

This study applied satellite radar imagery to identify flooded areas and examined post-flooding conditions using time-series satellite radar imagery for the development of flood damage mitigation strategies. Using time-series satellite radar images, this study constructed a map delineating areas vulnerable to frequent flood damage. The extracted flooded areas were combined with reference land use maps to examine flood damage by land use type. Major landuse types with severe flood damage were agricultural and forested areas. The analysis of the damage conditions, in terms of land use, served as the basis for developing flood damage mitigation policies, in conjunction with land use planning. The policies for flood damage mitigation can be summarized as land use regulations, land use planning, and flood damage mapping. A preventive measure to minimize flood damage of properties, which regulates developing areas with high flooding potential, is highly recommended. Although this study suggested a number of policies for flood damage mitigation, they represent only a small number of possible policies useful for mitigating flood damage and other environmental problems. Based upon the results of this study, it may be concluded that satellite radar imagery has great potential in providing basic data for large-scale environmental problems such as flooding and oil spills. Nevertheless, further examinations should be conducted and the application of satellite radar imagery should be used to examine other environmental problems.

• Journal of Korean Society of Forest Science
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• v.99 no.1
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• pp.125-130
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• 2010

The application of bioreactor culture techniques for plant micropropagation is regarded as one of the ways to reduce production cost by scaling-up and automation. In an attempt to optimize mass proliferation systems in Eucalyptus pellita, four types of bioreator systems including temporary immersion system with or without net were tested. Highest growth was achieved with 30-min flushes of medium at every 4-h intervals in TIN (temporary immersion with net) system. Results indicate over three-fold increase in shoot growth with the TIN system when compared with TIX (control: temporary immersion without net) system which is without net in bioreactor. Furthermore, plants produced from the TIN system increased total chlorophyll content, chlorophyll a/b and dry matter, giving higher yields of acclimatized plants. Our findings suggest that plantlet growth increases with appropriate exposure to media at correct intervals, as well as use of net for maintaining aerobic condition in the vessels. The TIN system thus has great potential for in vitro mass production of Eucalyptus clones commercially.

• Journal of Bio-Environment Control
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• v.12 no.4
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• pp.228-234
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• 2003

Various hydration treatments have been devised to improve the rate and univormity of seed germination as well as seed viability. Hydropriming and priming, the imbibitaion of seeds in distilled water and osmotic solutions, respectively, are useful techniques for early establishment of uniform seedlings. In this study, the optimum conditions were determined for hysropriming of cucumber seeds. Effects of hydropriming were also compared to those of osmotic priming. Seeds, hydroprimed with distilled water and primed with 50 mM $NaNO_3$at 20 for 24 hour, showd shorter number of days required to reach 50% of the final germination percentage ($T_{50}$), and mean number of days to germinate (MDG) that those untreated seeds. Hydroprimed with 10 mL distilled water showed better results in improving the rate of germination thatn other treatments tested. Hydropriming of the aged seeds improved germination percentage at 15$^{\circ}C$ and 25$^{\circ}C$. The $T_{50}$ and MDG values were reduced significantly by hydropriming of the aged seeds regardless of germination temperature. In addition to being simple and inexpensive, the hydropriming resulted in early germination at low temperature. he hydropriming was also effective in increase of germination percentage and normal seedlings.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.5 no.1
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• pp.123-132
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• 1985

The flexibility of base material gives considerable influences on seismic responses of a structure. The effects of relative stiffness between super-structure and base material on dynamic soil-structure interaction are evaluated by parametric studies. Two 5-story buildings are used for the study; one is shearwall structure with relatively higher fundamental frequency and the other is frame structure with relatively lower fundamental frequency. The structures are modeled as beam-sticks coupled with springs and dashpots representing the base material. Dynamic equilibrium equations of the soil-structure interaction system are sloved by mode superposition method using Rosset modal damping values. Soil-structure interaction effect is found to be major concern in seismic analysis of shearwall structure in most cases while it seldom becomes engineering problem in frame-type structure. It is also found that seismic responses at lower elevation of the super-structure are amplified though they decrease at higher elevation as soil-structure interaction effects of the system increase.

• Journal of Mushroom
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• v.13 no.3
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• pp.250-255
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• 2015

In this study spent mushroom substrate has ingredient raising rice bed soil. spent mushroom substrates are organic content is 60.72% were nitrogen - phosphoric acid - potassium is 1.39 - 0.89 - 0.81% of the chemical characteristics determine. Post-harvested mushroom substrates of the stabilization process, the temperature of the 20 days time progress in the pH of the rise and fall of temperature down were germination index also 77, as identified, Spent mushroom substrate bed soil for raising rice Ingredient to take advantage of the 20 days or more stabilization process needed to be investigated. Rice seed germination characteristic is in the common bed soil for raising rice ingredients manufactured control group and the comparison in spent mushroom substrate is 10% or less of a mixed experimental population of the germination rate is 82% was more than average days to germination and germination energy, even a statistical significant difference is or control group than good level was ok. Growth initial also spent mushroom substrate is 10% or less of a mixed experimental population of shoot dry matter (top) and grave less than control group higher as confirmed spent mushroom substrates are bed soil for raising rice ingredients are likely to take advantage of the high, as was the judge.

• Fire Science and Engineering
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• v.15 no.1
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• pp.100-107
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• 2001

A Interior material, a main cause of fire-growth and generating toxic gas when it burns, should be dealt with great care in life safety design. Nonetheless, it has been used recklessly with undue attention to its contribution to fire in particular in entertainment occupancy and causes many victims in fire. Therefore, this study attempts to examine the current use of interior material in Korea and find out what to be improved and enhanced in terms of related regulations. Based on the comparison and analysis of the Korea regulation with those of advanced nations, suggestions are made for an effective and efficient improvement and complement to the current system. What can be suggested from this study are as follows. The use of interior material should be controlled under the unified regulation of fire-safety codes. Code should be set up so that the current construction enforcement should be applied in retroactive to those entertainment buildings that obtained a license prior to the implementation of the system certifying that the building is fire-resistant and fire-protective. The legislation should be made to control the fire-protection facilities of small-sized, underground entertainments. It should be obliged to present the blueprint displaying the use of interior material at the time of changing occupancy. Or, it should be compelled to report changes that go way without permit to the administrative office. A compulsory provision should be set up to have a fire-resistant performance to movable furniture. The classification index designating the fire hazard of interior material by flame spread rate and smoke toxicity and its test method should be established.