• 한국해양학회지
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• v.30 no.4
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• pp.341-354
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• 1995

Fluorescence characteristic and amino acids composition of organic matter were determined from extracted seawater samples at eight stations in the East Sea of Korea. Organic compounds have been extracted onto C-18 Sep-Pak cartridges. Three dimensional excitation/emission fluorescence contouring of extracts showed two markedly distinct characterized fluoroscopies representing protein-like biomacromolecule and humic-like geomacromolecule. Protein-like biomacromolecule showing fluorescence maxima at 280 nm/330 nm (excitation/emission) were abundant in the surface mixed layer and then apparently decreased below the thermocline at most stations. It suggests that source of biomacromolecule is comely related with vigorous biological synthetic activity in the surface layer and bacteria decompose its biologically labile components near the thermocline and in the deeper layer. On the other hand, humiliate geomacromolecule showing fluorescence maxima at 330 nm/430 nm (excitation/emission) were low in the surface mixed layer implying photochemical oxidation and then increased below the thermocline at most stations. It suggests that geomacromolecule might be transformed by condensation of bio-refractoryorganic fraction after decomposition of biomacromolecule and particulate organic carbon derived from the surface mixed layer. HPLC measurements of amino acids showed similar composition between seawater and extracted organic macromolecule after hydrolysis. Glycine, serine and alanine were predominant, accounting for more than 50% of total amino acids. Dissolved free amino acids of seawater were more abundant in the surface layer(0.7∼1.8 uM) than the deeper layer (0.2∼0.4 uM). D/L racemic ratio of alanine of extracted organic matter showed lower value in the surface layer than the deeper layer. It suggests that biomacromolecule predominant in the surface layer is relatively young, rapidly recycling and biologically labile.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.35D no.9
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• pp.20-25
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• 1998

Cu removal rates for various SiO$_2$ trench pitch sizes and densities and AFM images of surface profiles after global planarization using Cu CMP technology are investigated. In the experimental results, Cu removal rates are increasing as the pattern densities and pattern pitches are getting high and low, respectively, and then decreasing after local planarization. The rms roughness after global planarization are about 120$\AA$. AFM images with a 50% pattern density for 1${\mu}{\textrm}{m}$ and 2${\mu}{\textrm}{m}$ pitches show that thicknesses of 120~330$\AA$ Cu interconnects have been peeled off and oxide erosion of Cu/Sio$_2$ sidewall is observed. However, AFM images with a 50% pattern density for 10${\mu}{\textrm}{m}$ and 15${\mu}{\textrm}{m}$ pitches show that 260~340$\AA$ thick Cu interconnects have been trenched at the boundaries of Cu/Sio$_2$ sidewall.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.22 no.2
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• pp.330-337
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• 2018

This paper proposes a technique to analyze the flatness characteristics of the attenuator at 10Hz to $50\text\tiny{MHz}$ on the basis of $1\text\tiny{kHz}$ using a Thermal Voltage Converter and AC measurement standard. In the proposed technique, the input voltage of the attenuator for each measuring frequency is supplied at the same rate as $1\text\tiny{kHz}$ using TVC, and the flatness characteristics of the attenuator are analyzed by the voltage variation indicated in the AC measurement standard. The results of the analysis of the attenuator flatness characteristics show that the maximum uncertainty of $866{\mu}V/V$ can be measured from $10\text\tiny{dB}$ to $70\text\tiny{dB}$ and the uncertainty is reduced by about 37% compared to $2.31\text\tiny{mV}$/V using the network measurement method. The improved attenuator flatness characteristic values can be applied to the frequency flatness calibration from 2.2V to 2.2mV at the low voltage of the AC measurement standard.

• Journal of IKEEE
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• v.15 no.4
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• pp.330-338
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• 2011

In this paper, a current-mode buck-boost converter using Multiple switching devices is presented. The efficiency of the proposed converter is higher than that of conventional buck-boost converter. In order to improve the power efficiency at the high current level, the proposed converter is controlled with PWM(pulse width modulation) method. The converter has maximum output current 300mA, input voltage 3.3V, output voltage from 700mV to 12V, 1.5MHz oscillation frequency, and maximum efficiency 90%. Moreover, this paper proposes watchdog circuits in order to ensure the reliability and to improve the performance of dc-dc converters. An electrostatic discharge(ESD) protection circuit for deep submicron CMOS technology is presented. The proposed circuit has low triggering voltage using gate-substrate biasing techniques. Simulated result shows that the proposed ESD protection circuit has lower triggering voltage(4.1V) than that of conventional ggNMOS(8.2V).

• Proceedings of the Korean Society of Crop Science Conference
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• 2022.10a
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• pp.330-330
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• 2022

In recent studies, cold plasma has been used to induce exudation of polyphenols and flavonoids from food materials, leading to enhancement of functional properties. And it is known that polyphenols interact with inflammation related metabolism. The objectives of this study were to investigate the effects of cold plasma treatments on the increase of total phenolic content (TPC), total flavonoid content (TFC), and anti-inflammatory activities of 'Sinpalkwang' peanut (Arachis hypogaea L.) hull. Plasma treatments were carried out using a dielectric barrier discharge gas exchange system at different radicals and temperatures (O₃-25℃, O₃-150℃, NO_x-150℃). Significant differences in TPC, TFC, and inflammatory mediator such as nitric oxide (NO) and tumor necrosis factor a (TNF-α) in lipopolysaccharide stimulated Raw 264.7 macrophages were observed between treated and non-treated peanut hull samples (p < 0.001). Cold plasma treated samples showed higher content (TPC: 2.87-2.93 mg/g sample, TFC: 0.96-0.98 mg/g sample) than non-treated sample (TPC: 2.47 mg/g sample, TFC: 0.78 mg/g sample). Cold plasma treated samples showed lower content of NO (3.3-5.0 uM) and TNF-α (141.4-162.2 ng/mL) than non-treated sample (NO: 11.1 uM, TNF-α: 210.2 ng/mL). This study suggests that cold plasma has potential to improve functionalities of food materials and that cold plasma treated peanut hull can be used as immune enhancing materials.

• Korean Journal of Environmental Agriculture
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• v.28 no.2
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• pp.165-170
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• 2009

The increase in P availability to rice under flooded soil conditions involves the reductive dissolution of iron phosphate and iron (hydr)oxide phosphate. However, since $NO_3^-$ is a more favourable electron acceptor in anaerobic soils than Fe, high$NO_3^-$ loads function as a redox buffer limiting the reduction of Fe. The effect of adding $NO_3^-$ on Fe reduction and P release in paddy soil was investigated. Pot experiment was conducted where $NO_3^-$ was added to flooded soil and changes of redox potential and $Fe_2^+$, $NO_3^-$ and $PO_4^{3-}$ concentrations in soil solution at 10 cm depth were monitored as a function of time. Redox potential decreased with time to -96 mV, but it was temporarily poised at about 330${\sim}$360 mV when $NO_3^-$ was present. Nitrate addition to soil led to reduced release of $Fe_2^+$ and prevented the solubilization of P. Phosphate in pore water began to rise soon after incubation and reached final concentrations about 0.82 mg P/L in the soil without $NO_3^-$ addition. But, in the soil with $NO_3^-$ addition, $PO_4^{3-}$ in pore water was maintained in the range of 0.2${\sim}$0.3 mg P/L. The duration of inhibition in $Fe_2^+$ release was closely related to the presence of $NO_3^-$, and the timing of $PO_4^{3-}$ release was inversely related to the $NO_3^-$ concentration in soil solution. The results suggest that preferential use of $NO_3^-$ as an electron acceptor in anaerobic soil condition can strongly limit Fe reduction and P solubilization.

• Korean Chemical Engineering Research
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• v.62 no.1
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• pp.13-18
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• 2024

To develop flexible electrode materials for wearable devices, we investigated the electrochemical characteristics of carbon fibers tow according to pretreatment. And an electrochemical non-enzymatic sensor was fabricated using glucose as a target. The carbon fibers tow was pretreated through desizing and activation processes, and activation was performed in two ways: chemical oxidation and electrochemical oxidation. Surface morphology of carbon fibers tow samples was observed by SEM and their electrochemical characteristics and sensing performance were investigated by cyclic voltammetry, electrochemical impedance spectroscopy and chronoamperometry. Carbon fibers tow samples showed improved electrochemical properties such as reduced R_et, ΔE_p, and increased I_p through pretreatment. And similar electrochemical properties were obtained with both activation methods. We selected electrochemically activated carbon fibers tow as the final electrode material for application of electrochemical sensor. The non-enzymatic glucose sensor based on this electrode has an enhanced sensitivity of 0.744 A/mM (in a linear range of 0.09899~3.75423 mM) and 0.330 mA/mM (3.75423~50 mM), respectively. Through this study, the possibility of using carbon fibers tow was confirmed as an electrode material. It is expected to be used as basic research for development of high-performance flexible electrode materials.

• Restorative Dentistry and Endodontics
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• v.12 no.2
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• pp.11-15
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• 1987

Thirty maxillary second premolars were fixed, decalcified, washed and embedded in celloidin to observe the root canal size and morphology at apical 5mm area. The results were as follows: 1. Single canaled teeth and two canaled teeth were approximately equal numbered. 2. Single canaled teeth have round canal but two canaled teeth have long, slender buccal canal and ovoid lingual canal. 3. The canal size of single canaled teeth was $380{\pm}30{\mu}m,\;340{\pm}22{\mu}m$, but that of buccal canal of two canaled teeth was $360{\pm}32{\mu}m,\;240{\pm}28{\mu}m$, lingual canal was $330{\pm}28{\mu}m,\;280{\pm}20{\mu}m$.

• Journal of Korean Society for Atmospheric Environment
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• v.5 no.1
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• pp.22-32
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• 1989

In order to assess the level of atmospheric pollution and to contribute the health improve ment of residents in Pusan, the authors measured the $CO, SO_2, NO_2, TSP, Noise, Pb, Cd, Cr and V$ level at 3 place by time from Jan. 1988 to Feb. 1988. THe places were Kukje, Daehyeon, Pujeon underground commercial floor. The results were as follows; 1. The range of concentration of air pollutants (1) CO : 0.5 - 3.0 ppm (2) $SO_2$ : 0.012 - 0.360 ppm (3) $NO_2$ : 0.018 - 0.089 ppm (4) TSP : 30 - 330 $\mug/m^3$ (5) Pb : 0.219 - 3.116 $\mug/m^3$ (6) Cd : 0.000 - 0.070 $\mug/m^3$ (7) Cr : 0.378 - 4.098 $\mug/m^3$ (8) V : 0.000 - 1.010 $\mug/m^3$ (9) Noise : 47 - 77 dB(A) 2. The level of all air pollutants were higher in the afternoon or night than in the morning. 3. The mean concentration of $SO_2$ in all places exceede the ambient air quality standard of $SO_2$,.

• Proceedings of the Korean Information Science Society Conference
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• 2000.10b
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• pp.464-466
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• 2000

오늘날 영상정보의 보편화로 효율적인 영상 검색 기술이 요구되고 있다. 최근 발표된 Color N$\times$M-grams 기반의 영상 검색 방법은 그 중의 하나이다. 그러나 이 방법은 영상의 특징을 추출한 벡터 Bin의 수가 많아서 검색을 위한 공간과 시간을 많이 필요로 하는 문제점을 가지고 있다. 이러한 문제를 보완하기 위해 본 연구에서는 영상의 국부성을 이용하여 Color N$\times$M-grams의 단점인 공간과 시간의 비효율성을 개선하고, GLCM의 결합으로 검색 효율을 향상시키는 연구를 수행하였다. WWW의 Color Draw Photo Album에 분류되어 있는 영상들과 미국의 코넬대학의 연구에 사용된 330개의 Benchmark 영상을 가지고 실험한 결과, 기존의 Color N$\times$M-grams에 비해 약 10배의 공간효율개선과 약 2배의 시간효율개선을 얻을 수 있었고, 검색율과 정확성공율에 있어서 각각 25%, 63% 향상되었다.