• 한국대기환경학회지
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• 제28권1호
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• pp.77-85
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• 2012

In this study, emission rates (ER) of biogenic volatile organic compounds (BVOCs) were measured by varying levels of photosynthetically active radiation (PAR). An appropriate plan for ozone reduction according to increasing ecology area ratio in future metropolitan areas was suggested. Several trees were selected as representative tree species in urban areas. Emission rates and composition ratios of monoterpene and isoprene emitted from these trees were estimated and compared. As a result, it was found that emission rates of BVOCs were considerably different depending on tree species. Especially, BVOCs emitted from Platanus orientalis and Quercus mongolica could significantly affect ozone increase in the metropolitan area, because the emission rates were several thousands to ten thousand times higher than those emitted from Zelkova serrata and Prunus serrulata. Furthermore, it was observed that emission rates of BVOCs by species increased maximum up to 10 times when PAR, which has close relations with temperature, rose. It was concluded that tree species such as Zelkova serrata et al., was appropriate for metropolitan areas since the species has low ozone potential and good landscape. Suppose this type of trees are planted on purpose in the urban areas, better ambient air quality will be promised in the future.

• The Korean Journal of Physiology
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• 제16권2호
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• pp.119-128
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• 1982

The frog truncus arterious were studied with conventional glass microelectrode technique in order to elucidate the underlying mechanism of spontaneous pacemaker activity. The analyses were focussed on the ionic nature of pacemaker current by changing the concentrations of extracellular $K^+$ and, $Na^+$, or by using blockers of K- and Ca-current and chronotropic transmitters. 1) The action potential of the spontaneously active truncus arteriosus has some characteristic feature of maximal distolic potential ranged from -65 to -75 mV, resting potential from -45 to -50 mV and overshoot voltage about +30 mV, respectively. Duration of the action potential taken from rapid upstroke to maximal diastolic potential was about 600 msec. Usual discharge rate was $25{\sim}30/min$ at room temperature $(18{\sim}20^{\circ}C)$. 2) The sensitivity of the resting membrane potential to change extracellular potassium concentrations $(0{\sim}12\;mM)$ was relatively low. Transient hyperpolarization was appeared in the 12 mM K Ringer after 10 min exposure to 0 mM K and it could be related to Na-pump reactivation by high potassium. 3) Reduction of extracellular sodium concetrations diminished the amplitude and frequency of the action potential. In Ringer solution containing 30% Na (substituted by equimolar Tris), spontaneous activity stopped but reappeared as very slow and small action potential. There was no spotaneous activity in zero Na Ringer solution. 4) Caesium(10 mM), K-current blocker decreased the frequency of the action potential and also pacemaker depolarization. Manganese (2 mM) known to be Ca-current antagonist, blocked spontaneous activity completely. 5) Adrenaline and acetylcholine had no chronotropic effect. But adrenaline increased the duration of plateau phase and the magnitude of the action potential in the follower cell. It is concluded that K-, Na-and Ca-current components are involved in the genesis of spontaneous activity of the frog truncus arteriosus like cardiac pacemaker tissues. But the insensitivity of truncus arteriosus to adrenaline and acetylcholine indicates that there are some different control mechanisms of spontaneous rhythm in two tissues.

• Fisheries and Aquatic Sciences
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• 제22권11호
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• pp.27.1-27.6
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• 2019

Background: In order to assess the high value-added use of the alginate-free residue of sea tangle, an animal study was performed to evaluate the functional activities and key compounds present. In the animal study, sea tangle and the alginate-free residue demonstrated good anti-hyperlipidemic and anti-arteriosclerotic abilities. Results: The functional compounds in the alginate-free residue of the sea tangle were effectively extracted by supercritical fluid extraction (SFE). The optimum extraction temperature and pressure were 40 ℃ and 6500 psi (M1) in the SFE, a better method in comparison to the conditions of 70 ℃ and 4500 psi (M2), respectively. The anti-atherosclerotic effects of the alginate-free residue of sea tangle (M1, M2) were investigated in Sprague-Dawley rats treated with poloxamer 407, Triton WR 1339, corn oil, and a high-fat diet. The M1 fraction reduced the serum lipid levels with greater efficacy than the M2 fraction. In the hyperlipidemic rats, treatment with M1 decreased the serum triglyceride (TG), total cholesterol (TC), and low-density lipoprotein-cholesterol (LDL-C) levels when compared to the levels in normal rats. Conclusion: Our results demonstrated that the alginate-free residue of sea tangle reduces serum TC, TG, and LDL-C. These results suggest that the alginate-free residue of sea tangle contains physiologically active components, such as fucosterol, that may exert beneficial effects in the prevention of atherosclerosis.

• 한국콘텐츠학회논문지
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• 제19권11호
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• pp.12-21
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• 2019

4차산업혁명시대에 드론은 새로운 기술과 접목할 수 있는 유연한 기기로 자리매김하였다. 드론은 처음에 군사용 무인 항공기로 개발되었으며, 지금은 다양한 분야(건설, 물류·운송, 소방·안전, 환경·기상, 농업, 뉴스·미디어, 등)에 활용되고 있다. 환경 기상 관측 부분에서 대기경계층은 지표면에 가까워 기상현상이 가장 활발히 일어나는 대기층으로 인간 활동에 밀접한 영향을 준다. 이러한 대기 경계층의 연구 수행을 위하여 하층 대기에 대한 정밀 관측이 필요하며, 이에 따른 관측 기술의 확보가 필수적이다. 기상 분야에서의 드론은 항공기, 라디오존데 등 기존 장비에 비하여 비교적 저렴한 유지비용으로 기상관측에 활용이 가능하며, 다양한 센서와 함께 활용할 경우, 대기경계층 및 국지 기상연구에 폭넓게 활용될 수 있다. 본 연구에서는 국립기상과학원에서 보유중인 드론에 복합기상센서 및 라디오존데 센서를 탑재후 연직 기상관측(온도, 습도) 실험을 수행함으로써 드론을 활용한 기상관측의 가능성을 확인하였다.

• Progress in Superconductivity
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• 제10권1호
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• pp.55-59
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• 2008

A Superconductor Flywheel Energy Storage System(SFES) mainly consists of a pair of non-contacting High Temperature Superconductor(HTS) bearings that provide very low frictional losses, a composite flywheel with high energy storage density. The HTS bearings, which offer dynamic stability without active control, are the key technology that distinguishes the SFES from other flywheel energy storage devices, and great effort is being put into developing this technology. The Superconductor Journal Bearing(SJB) mainly consists of HTS bulks and a stator, which holds the HTS bulks and also acts as a cold head. Static properties of HTS bearings provide data to solve problems which may occur easily in a running system. Since stiffness to counter vibration is the main parameter in designing an HTS bearing system, we investigate SJB magnetic force through static properties between the Permanent Magnet(PM) and HTS. We measure stiffness in static condition and the results are used to determine the optimal number of HTS bulks for a 100kWh SFES.

• 한국재료학회지
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• 제22권5호
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• pp.237-242
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• 2012

We report on the NO gas sensing properties of Al-doped zinc oxide-carbon nanotube (ZnO-CNT) wire-like layered composites fabricated by coaxially coating Al-doped ZnO thin films on randomly oriented single-walled carbon nanotubes. We were able to wrap thin ZnO layers around the CNTs using the pulsed laser deposition method, forming wire-like nanostructures of ZnO-CNT. Microstructural observations revealed an ultrathin wire-like structure with a diameter of several tens of nm. Gas sensors based on ZnO-CNT wire-like layered composites were found to exhibit a novel sensing capability that originated from the genuine characteristics of the composites. Specifically, it was observed by measured gas sensing characteristics that the gas sensors based on ZnO-CNT layered composites showed a very high sensitivity of above 1,500% for NO gas in dry air at an optimal operating temperature of $200^{\circ}C$; the sensors also showed a low NO gas detection limit at a sub-ppm level in dry air. The enhanced gas sensing properties of the ZnO-CNT wire-like layered composites are ascribed to a catalytic effect of Al elements on the surface reaction and an increase in the effective surface reaction area of the active ZnO layer due to the coating of CNT templates with a higher surface-to-volume ratio structure. These results suggest that ZnO-CNT composites made of ultrathin Al-doped ZnO layers uniformly coated around carbon nanotubes can be promising materials for use in practical high-performance NO gas sensors.

• 한국통신학회논문지
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• 제40권7호
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• pp.1347-1353
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• 2015

$0.13-{\mu}m$ CMOS 공정기술을 이용하여 10 Gb/s 4채널 수직공진 표면 광레이저 (VCSEL) 드라이버 어레이를 구현하였다. 높은 전류 해상도, 전력 소모 및 칩 면적의 향상을 위해 시분할 센싱기법을 사용한 디지털 APC/AMC가 최초로 채택되었다. 측정된 -3 dB 주파수 대역폭은 9.2 GHz이고, 소신호 이득은 10.5 dB, 그리고 전류 해상도는 폭넓은 온도 범위에 대해 10 Gb/s 까지 안정한 파장동작을 위한 1 mA/step이다. 제안된 APC/AMC는 5 ~ 20 mA 의 바이어스 전류 제어 및 5 ~ 20 mA 의 변조전류제어를 입증하였다. 4 채널 칩 소모전력은 최대 바이어스 및 변조전류 하에서 371 mW, 칩 사이즈는 $3.71{\times}1.3mm^2$이다.

• 한국패류학회지
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• 제18권2호
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• pp.67-76
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• 2002

1997년 7월부터 1998년 6월까지 제주도 함덕리 조간대에서 매월 채집한 흑백배말 (Cellana nigrolineata) 의 생식세포형성과정, 생식주기, 월별 난경 조성 및 생식소지수를 조사하였다. 생식소는 내장낭 내면, 복부 앞쪽에 위치하며, 성숙시기에 정소는 유백색을 난소는 짙은 갈색을 띠고 있다. 생식소지수는 수온이 상승하는 5월부터 서서히 증가하기 시작하여 8월에 최고 값을 나타냈다. 이후 9월에 감소하기 시작하여 8월에 비교적 낮은 값을 유지하였다. 생식주기는 생식소의 월별변화와 난모세포의 크기에 따라 회복기 (11-4월), 활성기 (3-6월), 완숙기 (5-10월) 그리고 방출기 (8-12월)로 구분되었으며, 주 산란기는 9-10월로, 연 1회의 산란시기를 갖는다. 흑백배발은 자웅이체로서 성전환 개체나 자웅동체의 개체는 없었다.

• 동굴
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• 제76호
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• pp.37-42
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• 2006

The Dielectric Barrier Discharge (DBD) is a nonequilibrium gas discharge that is generated in the space between two electrodes, which are separated by an insulating dielectric layer. The dielectric layer can be put on either of the two electrodes or be inserted in the space between two electrodes. If an AC or pulse high voltage is applied to the electrodes that is operated at applied frequency from 50Hz to several MHz and applied voltages from a few to a few tens of kilovolts rms, the breakdown can occur in working gas, resulting in large numbers of micro-discharges across the gap, the gas discharge is the so called DBD. Compared with most other means for nonequilibrium discharges, the main advantage of the DBD is that active species for chemical reaction can be produced at low temperature and atmospheric pressure without the vacuum set up, it also presents many unique physical and chemical process including light, heat, sound and electricity. This has led to a number of important applications such as ozone synthesizing, UV lamp house, CO2 lasers, et al. In recent years, due to its potential applications in plasma chemistry, semiconductor etching, pollution control, nanometer material and large area flat plasma display panels, DBD has received intensive attention from many researchers and is becoming a hot topic in the field of non-thermal plasma.

• 농업과학연구
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• 제35권1호
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• pp.25-32
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• 2008

This study was conducted to find an optimal combination rate of castor meal for the good qualitative compost and to estimate the humification grade by physico-chemical characterization and phyto-toxicity test during composting of the mixture with cow manure and castor meal. The material ratios of the compost which was mixed with cow manure(C), castor meal(C), and saw dust(S) were 5 : 1 : 4(CCS-1), 5 : 2.5 : 2.5(CCS-2) and 5 : 4 : 1(CCS-3) by volume to volume, and they were decomposed for 60 days. In the result, the changes of temperature in all treatments during composting radically increased more than $63.6^{\circ}C$ at the incipient stage, and gradually decreased around $42^{\circ}C$. At the 60 days after the treatment, pH was slowly increased from 7.0 to 8.0, and the C/N ratio was 12.3~13.8 at the final composting stage. The low C/N ratio value was caused by the castor meal with high nitrogen level(T-N 5.7%). G.I.(germination index) showed in the range of 77.5 to 82.6 in all treatments. Among all treatments CCS-1 was appeared to be the best condition for composting. Therefore, the combination rate of castor meal which was used for compost humification improvement could be recommended 10% to manufacture the good qualitative cow manure compost.