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        검색결과 12

        1.
        2023.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        UV and O3 are materials used in the water treatment process, and many studies have been reported to remove organic matters, contaminants, and microorganisms. In this study, we were investigated effects of Chirnomidae (Chironomus flaviplumus, Chironomus riparius), which are contamination indicator species to exposure UV and O3 for the survival rate, body color change and gene expression response. The survival rate of C. flaviplumus exposed to UV decreased to about 70% after 24 hours, and C. riparius about 50%. There was no change in the survival rate of C. flaviplumus exposed to O3, and C. riparius decreased to 95% after 10 minutes of exposure, but there was no change during the subsequent exposure time. In addition, UV and O3 exposure to the two species in body color faded in a time-dependent. In the HSP70 gene expression, C. riparius showed an increase in expression after UV exposure compared to the control group, and a significant difference was shown 12 hours after exposure (P<0.05). C. flaviplumus exposed to O3 showed a relatively low expression compared to the control group, and showed a significant difference at 10 minutes and 1 hour after exposure (P<0.05). These results reported the ecotoxicological effects on Chironomidae according to UV and O3 exposure. Therefore, the results of this study can be used as basic data to understand the effects of UV and O3, which are disinfectants used in water treatment plants, on Chirnomidae entering plants. Key words: Chironomus flaviplumus, Chironomus riparius, UV, O3, acute toxicity, survival
        4,000원
        2.
        2012.11 구독 인증기관 무료, 개인회원 유료
        개인투자자들은 자신이 지지한 정당이 집권을 하였을 경우 경제상황이 좋아질 것이 라는 기대감(expectation)을 갖게 된다. 이에 따라 개인투자자들은 지지한 정당이 집권 하였을 때, 경제의 불확실성(uncertainty)이 줄어들고 주가도 상승할 것이라고 믿는 경 향이 있다. 이러한 개인투자자들은 실제로 주식투자 규모를 늘려가는 상황을 만들며, 소형주(small cap)를 비롯하여 가치주(value stocks), 경기민감주 등에 대한 투자규모 를 늘리는 경우가 흔히 발생하고 있다. 이와 같은 새로운 정부에 대한 기대감이 반영 되면서 새로운 정부의 집권 초기에 이들 개인투자자들은 주식보유기간을 보다 길게 가져가려는 경향도 보인다. 반면에 개인투자자들의 경우 자신이 지지하지 않는 집권정 부가 들어섰을 때 경제의 불확실성(uncertainty)이 증가한다고 판단하여 보유주식을 처 분하려는 경향이 증대되고 있다. 한국의 경우 개인투자자들의 투표성향이 체감 소득수 준 및 집권정부별 경제정책에 따라 영향을 받을 수 있는 것으로 나타나 주가수익률 등의 움직임에 주목할 필요가 있다고 판단된다.
        4,000원
        3.
        2012.04 구독 인증기관 무료, 개인회원 유료
        이 논문은 기존의 포트폴리오와 관련된 모형에 경기변동(business cycle)과 관련된 변수들을 포함하였을 경우 경기변동이 개인투자자들의 현금 및 주식보유를 통한 자본 이득 극대화와 어떤 관련성이 있는지와 관련된 것이다. 기존 문헌들을 살펴보면, 개인 투자자들은 경기호황기에는 모멘텀 투자와 소형주와 성장주 등에 포트폴리오를 분산 투자하지만 경기가 침체기(recession)에 들어설 경우 수익률이 급등락 하는 특성을 지 니는 소형주(small cap)에 집중적인 투자를 하는 성향을 나타내고 있다. 한편 이 논문의 분석결과에 따르면, 경기안정과 금리안정정책, 물가안정 등은 서로 상충관계(trade-off)에 놓여 있음에도 불구하고 코스피 수익률과 코스닥수익률에 모두 향후 영향을 미칠 것으로 판단된다. 이는 현재까지의 정책조합(policy mix)보다 더 정 교하고 타이밍을 잘 포착하지 않으면 정책실패에 따른 경기와 물가불안이 동시에 나 타나는 스태그플레이션(stagflation)으로 이어질 수 있음으로 정책집행의 효율성이 어 느 때보다도 중요해 질 것으로 보인다.
        4,000원
        4.
        2008.04 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The objective of the present study is to investigate the increase in the functional characteristics of a substrate by the formation of a thin coating layer. Thin coating layers of have high potential because exhibits high hardness. Shock induced reaction synthesis is an attractive fabrication technique to synthesize uniform coating layer by controlling the shock wave. Ti and Si powders to form using shock induced reaction synthesis, were mixed using high-energy ball mill into small scale. The positive effect of this technique is highly functional coating layer on the substrate due to ultra fine substructure, which improves the bonding strength. These materials are in great demand as heat resisting, structural and corrosion resistant materials. Thin coating layer was successfully recovered and showed high Vickers' hardness (Hv=1183). Characterization studies on microstructure revealed a fairly uniform distribution of powders with good interfacial integrity between the powders and the substrate.
        4,000원
        5.
        2008.04 구독 인증기관 무료, 개인회원 유료
        미국 센서스 뷰로 데이터에 의하여 2차대전 후 민주당정부와 공화당정부의 실질 세전 소득증가율의 차이를 살펴볼 때 민주당정부 기간동안에 계층간의 소득불균형이 시정되면서 저소득계층의 소득증가율이 상대적으로 더 높았음을 알 수 있다. 반면에 공화당정부 기간동안에는 소득불균형이 심화되면서 저소득계층보다 고소득계층의 소득증가율이 더 높았다. 소득계층에서 하위 20%의 계층은 공화당정부의 기간동안에 비하여 민주당정부의 기간에 4배의 높은 소득증가율을 가졌다. 이는 양 정부별 실업률 차이에서 비롯되는 데 민주당정부의 기간 동안에 평균 30% 낮았으며 GDP성장률은 평균 30% 높았음에도 영향을 받은 것으로 판단된다. 이러한 정부별 차이는 1980년대 이후 세후 소득증가율에서도 나타나고 있다. 한편, 실증분석 결과에 따르면 한국의 경우 미국에서와 같이 저소득계층이 고소득계층 보다 거시경제정책에 따른 영향을 더 많이 받고 있음을 알 수 있었으며, 특히 신정부에서는 이전보다 적극적인 통화정책을 적절한 타이밍(timing)으로 실시하여야 할 필요성이 나타났다.
        5,100원
        6.
        2007.11 구독 인증기관 무료, 개인회원 유료
        USA has distinct differences of economic policy by a ruling party. And, USA economy has mainly influenced on it of Korea. So, we examine whether a ruling party of Korea has different regime including rate of return in stock market. The Republican Party and Democratic Party have based on Milton Friedman and Keynes economy at each other's economic policy in the USA The Republican Party and Democratic Party have different interest level and excess return on equity, GDP growth rate, unemployment rate. Also, a ruling party of Korea has different regime and economic activity in this paper.
        4,600원
        8.
        2003.06 KCI 등재 서비스 종료(열람 제한)
        In order to examine if arsenic, one of environmental stresses, contributes to hypertension as one of cardiovascular pathological factors, this study was performed in vivo and in vitro, using intacted or pithed rats and aorta ring preparation, respectively. And also the relationship between expression of heat shock protein (HSP) 90 and vasoactives-induced contractile response was elucidated. To measure blood pressure, the carotid arterial pressure was recorded on physiograph(Grass Co. 79E) connected to strain gauge. On the other hand, contractile response of vascular ring preparation isolated from rat was determined in organ bath and was recorded on physiograph connected to isometric transducer. And HSP was detacted by Western blotting whole cell lysis. Preganglionic nerve stimulation was increased by 26.0% in arterial pressure of rat treated with arsenic. Vascular contractile response was monitored and HSP were measured by Western blotting of whole lysis prepared from samples exposed with 0, 0.5, 1, 2 and 4 mM of arsenic for 8 hours. The dose-vascular responses of potassium chloride were augmented by increasing dose of arsenic in the strips exposed to arsenic for 8 hours, and were not augmented for 1, 3, 5 hours. And the response of relaxation of rat aorta induced by histamine was not influenced by arsenic stress. The increase of HSP 90 expression in rat aorta was pronounced at 8 hours after 4 mM of arsenic treatment, but HSP 60 expression was not. Arsenic stress not only increased the expression of HSP 90 in the rat aorta, but also augmented contractions to potassium chloride. These results indicated that arsenic stress was sufficient to induce heat shock protein 90, resulting in increased vascular contractility in rat aorta.
        9.
        1997.02 KCI 등재 서비스 종료(열람 제한)
        The objective of this study was to examine the transient response to hydraulic shocks in an inverse fluidized bed biofilm reactor(IFBBR) for the treatment of apartment sewage. The hydraulic shock experiments, when the system were reached at steady state with each HRT 12, 7, and 4hr, were conducted by changing twice HRT per day during 3days. The SCOD, SS, DO, and pH of the effluent stream were increased with hydraulic shock, but easily recovered to the steady state of pre-hydraulic shock condition. In spite of hydraulic shock, there were not much variation of biomass concentration, biofilm thickness, and biofilm dry density.
        11.
        1994.09 KCI 등재 서비스 종료(열람 제한)
        The objective of this study was to examine and compare to transient response to quantitative and hydraulic shocks which produce equal changes in mass rate of organic feed in aerobic fixed-film process. The general experimental approach was to operate the system at several growth rates under steady-state(pre-shock) conditions, then to apply step changes during day 3 in dilution rate(hydraulic shock), or feed concentration(quantitative shock) at the same organic mass loading rate. Performance was assessed in both the transient state and the new steady-state (post-shock). Shock load of different type did not produced equivalent disruptions of effluent quality for equal increases on mass loading rate. Based on effluent concentrations, a hydraulic and a quantitative shock at the same mass loading caused equal increase in total effluent COD, but the increase was primarily a result of suspended solids the hydraulic shock and COD in the quantitative shock, The time which effluent COD came to peak values were about 32∼48 hours at the low organic loads and 52∼72 hours at the high organic loads, respectively. A quantitative shock produced a much greater increase in effluent COD than did a hydraulic shock at the same mass loading. Mean and peak values of effluent concentration were increased in 2.8∼4.2 times at low organic loading rate, 5.2∼6.6 times at the high organic loading rate respectively.
        12.
        1993.12 KCI 등재 서비스 종료(열람 제한)
        A number of experiments were conducted in order to investigate the organic removal efficiency and biomass characteristics according to the organic shock loading rate in a fluidized bed biofilm reactor. At the operation conditions of HRT, 8.44 hour, superficial upflow velocity, 0.9 ㎝/sec and temperature, 22±1 ℃, the removal efficiency of SCOD was founded to be 96.5, 92 and 90 % with the organic shock loading rate of 3.5, 10.8 and 33 kgCOD/㎥·day, respectively. Within the F/M ratio ranged 0.4 to 2.0 ㎏COD/㎏VSS·day, the SCOD removal efficiency was shown as 90% at F/M ratio of 2.0 ㎏COD/㎏VSS·day, but the TCOD removal efficiency was 72 % at F/M ratio of 1.8 kgCOD/kgVSS·day. The average biomass concentrations were 7800, 14950 and 27532 ㎎/l on the organic shock loading rate of 3.5, 10.8 and 33 ㎏COD/㎥·day, respectively. This result was agreed with the fact that more biomass could be produced at high concentration of substrate, but some biomass was detached at the onset of shock and easily acclimated at the shock condition.