• The Optical Journal
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• s.137
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• pp.15-18
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• 2012

산업연구원에서 발표한 '2012년 경제 산업 전망'에 따르면 우리나라의 2012년 국내경제는 연중 다소 부진한 모습을 보이면서 3%대 중반의 성장을 보일 것으로 전망된다. 수출은 세계경제 둔화에 따른 물량 증가율 하락, 유가안정에 따른 가격 상승세 소멸로 전년에 비해 크게 낮아진 7% 내외의 증가(통관기준)가 예상되며 수입 역시 국내경기 둔화와 유가 및 원자재가 안정에 따른 수입단가 안정으로 전년보다 증가세가 크게 둔화되어 연간 8%대 증가가 전망된다. 2012년 산업분야에서 IT제품군은 정보통신기기의 호조 지속과 가전의 수요 회복이 예상되며, 반도체와 디스플레이는 전년도의 마이너스 성장에서 완만하나마 회복기조로 전환될 것으로 보인다. 소재산업군은 설비능력 확대에 대응한 적극적인 수출시장 개척에 힘입어 1-5%의 완만한 증가율을 보일 전망이다.

• The Korean Journal of Financial Management
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• v.16 no.1
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• pp.155-170
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• 1999

이 논문은 거시경제변수가 유럽, 호주, 한국의 주식시장 변등성에서 시간에 따른 변화(Time Variation)를 설명할 수 있는지에 관하여 조사하는 데에 목적을 두고 있다. 그리고 이 논문은 미국에서 발표된 논문들의 결과와 달리 많은 경우에서 주식시장 변동성의 시간에 따른 변화가 과거의 화폐적 또는 실물적 거시경제 요소의 변화 가능성에서 통계적으로 유의하게 영향을 받는 지를 알 수 있었다. 따라서 자본 및 포트폴리오 배분에 대한 중요한 의미를 가지고 있다. 한국의 경우 경제회복에 따라 통화와 산업생산의 변동성 증가가 이뤄지면 주식시장의 성장에 중요한 역할을 할 수 있을 것이다. G7 국가 중에서 상대적으로 소규모국가인 이태리와 네덜란드에서도 위에서와 같은 결과들을 발견할 수 있었다. 한편 한국에서 특이한 점은 경제회복 이후에는 산업생산증가율의 증가가 통화량의 증가보다 더 주식시장에 중요한 영향을 줄 것임을 알 수 있다.

• Journal of the Korean Society for Precision Engineering
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• v.14 no.2
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• pp.145-151
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• 1997

In this paper, we discuss the cathode ray tube(CRT) glass bulb stress and sagging recovery by the contact band pressure using finite element method. We analyzed the band pressure and stress using contact element method between band and bulb before and after banding process which was conducted to decrease the stress concentration using finite element method, and calculated sagging recovery. The analysis results were confirmed by experiments using strain gauge and sagging recovery test apparatus.

• The Korean Journal of Financial Management
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• v.17 no.2
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• pp.175-209
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• 2000

본 연구는 프로그램매매가 주가지수 선물시장 및 현물 주식시장의 수익률 변동성에 미치는 효과에 대해서 일중 수익률 및 프로그램매매자료를 이용하여 분석을 시도하였다. 실증분석을 통해서 관찰된 결과를 살펴보면 대부분 선진국 시장에서 보고된 결과와 일치하였다. 우선 프로그램매매가 증가할수록 현물 주식시장에서의 변동성은 증대하는 것으로 나타났으나 선물시장에서는 그러한 일관성 있는 관계를 발견하지 못하였다. 프로그램매매 발동 직후 선물 및 현물시장의 수익률은 반전현상을 나타냈으며 특히 현물시장의 가격변화가 선물시장에 비해서 큰 것으로 관찰되었다. 그러나 이러한 선물시장과 현물시장에 있어서의 가격반전 현상이 시장 유동성에 미치는 경제적 영향은 선물만기일과 같이 특정시간대에 프로그램매매가 집중되지 않는 한 경미한 것으로 판단되었다. 프로그램매매 특히 차익거래는 선물 가격과 현물 가격간의 균형 관계가 일시적인 수급상황에 따라 이발될 경우 이를 다시 균형 상태로 회복시켜 줌으로써 시장의 효율성을 증대시키는 주요한 연결통로로서의 역할을 수행한다. 특히 두 시장간의 균형 상태는 선물 시장보다는 현물 주식시장에서의 활발한 매매 활동을 통하여 이루어짐을 알 수 있었다. 결론적으로 국내시장에서 차익거래는 시장의 위험을 증대시키는 부정적인 측면보다는 시장의 효율성을 증진시키는 긍정적인 순기능이 많은 것으로 관찰되었다.

• Journal of Korean Society of Environmental Engineers
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• v.28 no.2
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• pp.197-206
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• 2006

This study evaluated the effect of ultrasonic irradiation on improving the flux and cleaning efficiency in membrane process which is widely applied for the treatment of landfill leachate. The experiments on improvement of membrane flux according to the types of membranes(hallowfiber microfiltration, MF and tubular ultrafiltration, UF) were performed with changing frequency($40{\sim}120$ kHz), intensity ($200{\sim}500$ W) and irradiation time of ultrasound as well us operation pressure($0.1{\sim}2.3kg/cm^2$). Membrane was fouled for the first 50 min with primary treated leachate and then the change in flux according to ultrasonic irradiation period was observed for 70 min. Parameters influenced to the recovery ratio corresponding the net flux on pure water and to the enhancement ratio applied after ultrasonic irradiation on the flux were analyzed. In same condition, the flux was improved in proportion to ultrasonic intensity while the improvement of flux was inversely proportional to ultrasonic frequency. The cleaning effect of membrane was delayed and reduced when operation pressure of membrane was high. The recovery ratio and enhancement ratio for $0.1{\mu}m$ MF membrane were 10% and 500%, respectively while those were maximized at $75{\sim}98%\;and\;40{\sim}50%$ for UF membrane for 10,000 and 100,000 MWCO, respectively. In conclusion, it was confirmed that ultrasonic cleaning using mechanical vibration is alternative to water or chemical cleaning for improving membrane flux.

• Journal of Chest Surgery
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• v.31 no.9
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• pp.837-844
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• 1998

Background: Adenosine is secreted by myocardial cells during myocardial ischemia or hypoxia. It has many beneficial effects on arrhythmias, myocardial ischemia, and reperfusion ischemia. Although many investigators have demonstrated that cardioplegia that includes adenosine shows protective effects in myocardial ischemia or reperfusion injury, reports of the optimal dose of adenosine in cardioplegic solutions vary. We reported the results of beneficial effects of single dosage(0.75 mg/Kg/min) adenosine by use of self-made Langendorff system. But it is uncertain that dosage was optimal. The objective of this study is to determine the optimal dose of adenosine in cardioplegic solutions. Material and Method: We used a self-made Langendorff system to evaluate the myocardial protective effect. Isolated rat hearts were subjected to 90 minutes of deep hypothermic arrest(15$^{\circ}C$) with modified St. Thomas' Hospital cardioplegia including adenosine. Myocardial adenosine levels were augmented during ischemia by providing exogenous adenosine in the cardioplegia. Three groups of hearts were studied: (1) group 1 (n=10) : adenosine - 0.5 mg/Kg/min, (2) group 2(n=10): adenosine -0.75 mg/Kg/min, (3) group 3 (n=10) : adenosine -1 mg/Kg/min. Result: Group 3 resulted in a significantly rapid arrest time of the heart beat(p<0.05) but significantly slow recovery time of the heart beat after reperfusion(p<0.05) compared to groups 1 and 2. Group 2 showed a better percentage of recovery(p<0.05) in systolic aortic pressure, aortic overflow volume, coronary flow volume, and cardiac output compared to groups 1 and 3. Group 1 showed a a better percentage of recovery(p<0.05) in the heart rate compared to the others. In biochemical study of drained reperfusates, CPK and lactic acid levels did not show significant differences in all of the groups. Conclusion: We concluded that group 2 [adenosine(0.75 mg/Kg/min) added to cardioplegia] has better recovery effects after reperfusion in myocardial ischemia and is the most appropriate dosage compared to group 1 and 3.

• Membrane Journal
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• v.18 no.1
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• pp.65-74
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• 2008

NOM and fine particles are the main target materials in water treatment using membranes. Particularly, humic substances extracted from soils are frequently used in many fundamental studies representing natural organic matter in raw water for drinking water treatment. In this study, ultrafiltration (UF) of artificial humic water and natural river water was conducted and the characteristics of removal efficiency and permeability were compared. In the UF of river water, the transmembrane pressure increased in the same pattern with that of 5 mg/L humic water. For the removal of organic matter and fine particles, however, two types of feed water had shown different trends. Kaolin particles and humic acids added to artificial water were better removed, while colloids and organics in natural water were relatively poorly removed. From the $UV_{254}$ and GPC analyses, it seemed that the hydrophobicity and size of humic substances contributed to the greater removal of organic matter. The UF membrane applied for humic water also showed a higher flux recovery by caustic chemical cleaning than that for river water.

• Membrane Journal
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• v.29 no.6
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• pp.339-347
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• 2019

Forward osmosis (FO) is operated at a lower pressure than reverse osmosis (RO), which has great advantages in terms of fouling control, maintenance, membrane cleaning, and potential energy reduction. In particular, since the membrane fouling layer of the forward osmosis process has a relatively loose and dispersed property, it is possible to control the membrane fouling by physical cleaning, unlike the reverse osmosis process. However, existing studies do not apply the proper cleaning flow rate for forward osmosis physical cleaning, and thus there is a limit that the optimal operation can not be performed. Therefore, this study aims to evaluate the justification of proper flow rate that can show high efficiency cleaning with economical energy amount. The membrane fouling experiments of the forward osmosis process were maintained at a circulating flow rate of 8.54 cm/s and the recovery rates were compared with the three cleaning flow rates. As a result of this experiment, it was confirmed that the 2 × speed cleaning showed the same efficiency as the water permeability recovery rate of the 3 × speed cleaning, and it was confirmed that the 2 × speed cleaning was an appropriate flow rate with high cleaning efficiency and economical SEC.

• Membrane Journal
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• v.27 no.1
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• pp.68-76
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• 2017

Flat membrane with $0.4{\mu}m$ pore size was prepared with PVdF (polyvinylidene fluoride) nanofiber, which has the advantages such as excellent strength, chemical resistance, non-toxicity, and incombustibility. The spiral wound module was manufactured with the flat membrane and a woven paper. Hybrid water treatment process was composed of the PVdF nanofibers spiral wound microfiltration and granular activated carbon (GAC) adsorption column. Effect of GAC packing mass was investigated by comparing the case of recycling or discharging the treated water using the synthetic solution of kaolin and humic acid. After each filtration experiment, water back-washing was performed, and recovery rate and filtration resistances were calculated. Also, effect of GAC adsorption was compared by measuring turbidity and $UV_{254}$ absorbance. As a result, there was no effect of GAC packing mass on turbidity treatment rate; however, the treatment rate of $UV_{254}$ absorbance was 0.7~3.6% for recycling the treated water, and increased to 3.2-5.7% for discharging the treated water. In the case of recycling the treated water, reversible filtration resistance ($R_r$) and irreversible filtration resistance ($R_{ir}$) trended to decrease as increasing GAC packing mass; however, total fitration resistance ($R_t$) was almost constant, and recovery rate of water back-washing trended to increase a little.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.21 no.3
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• pp.103-111
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• 2016

Seasonal dynamics of kelp forest-forming algae, Ecklonia cava population formed following the large-scale disturbance by Typhoon 'Bolaven' in August 2012 were investigated in Jeju Island, Korea. Morphological characteristics, recruits density, mortality rate, total density and biomass were monitored bimonthly from June 2013 to June 2015. Total and longest blade lengths, and individual weight of E. cava showed distinct seasonal trends. Stipe length increased from winter to spring, but did not show increase or reduced from summer to autumn. This indicates that morphological characteristics of E. cava are mainly affected by the change of blades. The optimal temperature for E. cava growth was about $15-18^{\circ}C$ during winter to spring while the growths were inhibited at the water temperature above $20^{\circ}C$ during summer. E. cava exhibited very low recruitment during spring-summer. However, high recruitment was observed on April 2015 when canopy cover was very low due to low density. This indicates that recruitment of E. cava was controlled not by seasonal effects but by physical factors such as canopy and space. The mortality rate of juvenile plants was highest due to their unstable settlement. By June 2015, 34 months after the disturbances, E. cava was almost recovered to the pre-disturbance population size structure. These results suggest that recovery of kelp forest following the large-scale disturbance requires a considerable period of time (more than three years). This study should provide valuable ecological information on management, restoration and protection of kelp species.