• 한국대기환경학회:학술대회논문집
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• 한국대기환경학회 2009년도 추계학술대회 논문집
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• pp.587-588
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• 2009

• International Journal of Oral Biology
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• 제41권4호
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• pp.243-251
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• 2016

This study was undertaken to achieve a high bleaching efficacy with plasma, through longer application and reparative bleaching processes, by different shade evaluation methods. Extracted human teeth were divided into 6 groups (n=10). All teeth were treated in pairs. Low concentration of 15% carbamide peroxide (CP) was applied, with and without plasma, for 10, 20, and 30-min tooth bleaching, respectively. The bleaching procedure was repeated once daily for four days. The teeth were maintained in a moist environment provided by artificial saliva. The Vitapan Classical shade guide and Commission Internationale de L'Eclairage (CIELAB) color system were collectively used to measure the bleaching efficacy. Color evaluation was statistically analyzed using Student t-test and one-way analysis of variance (ANOVA) complemented by Tukey's test. Combining the plasma with 15% CP showed significantly greater color changes compared to bleaching without plasma (p<0.05). A high bleaching efficacy with plasma is proportional to the repetitive application and the treatment time. A 30-min application with plasma provided the best bleaching. Repetitive bleaching showed lower probability of color relapse of the bleached tooth. The color change by shade guide correlated with the changes in CIELAB color system. A value of 1 color change units (CCU) conversion factor for overall color change (${\Delta}E$) values comparisons was 3.724 values. The two measuring methods provide a more accurate correspondence of color change. The repetitive and longer application for tooth bleaching, combined with plasma, has a strong bleaching effect and produces whiter teeth.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제48권3호
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• pp.215-220
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• 1999

$SO_2$and CO gas removal characteristics of a wire-to-cylinder type nonthermal discharge plasma reactor in various applied voltage (-dc, ac, fast rising pulse and high frequency pulse) and a crossed dc magnetic field have been investigated. The experiment has been emphasized on the oxidizing characteristics of $SO_2$ and CO gas by $O_3$ and the applying of a crossed magnetic field, which would induce the cyclotronic and drift motions of electrons making the residual time longer in the removal airgap space. And it also would enhance the energy of electrons and the electrophysicochemical actions to remove the pollutant gases effectively. It is found thatthe corona onset voltage and the breakdown voltage were decreased with increasing the crossed magnetic field and decrease initial fed $SO_2$and CO concentration. As a result, a higher ozone generation and $SO_2$ and CO gas removal rate of 20[%] can be obtained with -dc, ac and fast rising pulse corona discharges in the crossed dc current-induced magnetic field. But high frequency pulse didn't show effect in applying of a crossed magnetic field.

• 한국식품과학회지
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• 제51권6호
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• pp.551-557
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• 2019

본 연구는 소비자들의 식품안전과 위생에 대한 요구가 강해짐에 따라 식중독의 위험에 노출되어 있는 분말식품 중 전세계적으로 널리 사용되는 향신료 중 하나인 후춧가루의 비가열 살균 처리 방법에 따른 향미특성 변화를 비교 분석하였다. 색도 측정 결과 색도차(ΔE)는 저온 플라즈마와 자외선 살균처리 후에도 육안에 의한 인식 한계인 1.5 내외로 유지되었고, 광펄스 처리 후에는 6.58로 큰 차이를 보였다. Piperine 함량 정량 결과는 살균 전 후추가 10.7±0.53 mg/g로 가장 많았으며 자외선 살균처리(9.5±0.35 mg/g), 저온 플라즈마 살균처리(9.0±0.15 mg/g), 광펄스 살균처리(4.4±0.17 mg/g) 순으로 광펄스 58.9%, 저온 플라즈마 15.9%, 자외선 11.2%의 감소율을 보였다. 전자코 분석 결과 살균 처리 전후가 제 1주성분에 의해 두 그룹으로 구분되어 명확하게 향의 차이가 나타났으며, 제 1주성분과 제 2주성분에 의해서는 세 개의 그룹으로 나뉘었다. 강도평가 결과 살균처리 전, 광펄스, 저온 플라즈마, 자외선 살균처리 후 순으로 후추 향과 맛이 강하다고 응답했으며, 광펄스와 저온 플라즈마 살균처리 후의 후추는 유의적인 차이를 보이지 않았다. 강도평가 결과와 piperine 함량 정량과는 차이가 있었으며, 전자코 분석 결과와는 유사했다. 정량적 묘사분석(QDA)를 통해 13개의 관능적 언어가 개발되었다. 살균처리 후의 시료가 마른 솔잎향과 떫은맛, 고소한맛을 제외한 모든 항목에서 살균처리 전의 시료보다 관능적 특성이 낮게 나타났다. 이를 통해 살균처리 방법에 따라 후추향과 맛에 영향을 끼쳤음을 알 수 있었다. 또한 piperine 함량을 통해 후추 맛의 강도를 평가하기에는 어려움이 있으며 전자코 분석을 통해서 후추향의 강도를 평가하는데 중요한 자료로 사용될 수 있다고 판단된다.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2000년도 제21회 KOSCO SYMPOSIUM 논문집
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• pp.33-46
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• 2000

In the present study, a systematic chemical kinetic calculations were made to investigate the augmentation of NO-$NO_2$ conversion due to the addition of various hydrocarbons (methane, ethylene, ethane, propene, propane) in the nonthermal plasma treatment. It is included in the present conclusion that the reaction between hydrocarbon and oxygen radicals induced by electron collision, is believed to be a primarily process for triggering the overall NO oxidation and the eventual NOx reduction. Upon the completion of the initiating step, various radicals (OH, $NO_2$ etc.) successively produced by hydrocarbon decomposition form the primary path of NO-$NO_2$ conversion. When the initiating step is not activated, hydrocarbon consumption rate appeared to be very low, thereby the targeted level of NO conversion can only be achieved by the addition of more input energy. Present study showed ethylene and propene to have higher affinity with 0 radical under all conditions, thereby both of these hydrocarbons show very fast and efficient NO-$NO_2$ oxidation. It was also shown that propene is superior to ethylene in the aspect of NOx removal.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2000년도 제20회 KOSCO SYMPOSIUM 논문집
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• pp.178-188
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• 2000

In the present study, a systematic chemical kinetic calculations were made to investigate the augmentation of $NO-NO_{2}$ conversion due to the addition of various hydrocarbons (methane, ethylene, ethane, propene, propane) in the nonthermal plasma treatment. It is included in the present conclusion that the reaction between hydrocarbon and oxygen radicals induced by electron collision, is believed to be a primarily process for triggering the overall NO oxidation and the eventual NOx reduction. Upon the completion of the initiating step, various radicals (OH, $HO_{2}$ etc.) successively produced by hydrocarbon decomposition form the primary path of $NO-NO_{2}$ conversion. When the initiating step is not activated, hydrocarbon consumption rate appeared to be very low, thereby the targeted level of NO conversion can only be achieved by the addition of more input energy. Present study showed ethylene and propene to have higher affinity with 0 radical under all conditions, thereby both of these hydrocarbons show very fast and efficient $NO-NO_{2}$ oxidation. It was also shown that propene is superior to ethylene in the aspect of NOx removal.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제44회 동계 정기학술대회 초록집
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• pp.141-141
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• 2013

We have generated the needle-typed nonthermal plasma jet by using an Ar gas flow at atmospheric pressure. Diagnostics of electron temperature anddensity is critical factors in optimization of the atmospheric plasma jet source in accordance with the gas flow rate. We have investigated the electron temperature and density of plasma jet by selecting the four metastable Ar emission lines based on the atmospheric collisional radiative model and radial profile characteristics of current density, respectively. The averaged electron temperature and electron density for this plasma jet are found to be ~1.6 eV and ~$3.2{\times}10^{12}cm^{-3}$, respectively, in this experiment. The densities of OH radical species inside the various bio-solutions are found to be higher by about 4~9 times than those on the surface when the argon bioplasma jet has been bombarded onto the bio-solution surface. The densities of the OH radicalspecies inside the DI water, DMEM, and PBS are measured to be about $4.3{\times}10^{16}cm^{-3}$, $2.2{\times}10^{16}cm^{-3}$, and $2.1{\times}10^{16}cm^{-3}$, respectively, at 2 mm downstream from the surface under optimized Ar gas flow 250 sccm.

• 천문학회지
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• 제46권1호
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• pp.49-63
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• 2013

Nonthermal radiation from supernova remnants (SNRs) provides observational evidence and constraints on the diffusive shock acceleration (DSA) hypothesis for the origins of Galactic cosmic rays (CRs). Recently it has been recognized that a variety of plasma wave-particle interactions operate at astrophysical shocks and the detailed outcomes of DSA are governed by their complex and nonlinear interrelationships. Here we calculate the energy spectra of CR protons and electrons accelerated at Type Ia SNRs, using time-dependent, DSA simulations with phenomenological models for magnetic field amplification due to CR streaming instabilities, Alf$\acute{e}$enic drift, and free escape boundary. We show that, if scattering centers drift with the Alf$\acute{e}$en speed in the amplified magnetic fields, the CR energy spectrum is steepened and the acceleration efficiency is significantly reduced at strong CR modified SNR shocks. Even with fast Afv$\acute{e}$nic drift, DSA can still be efficient enough to develop a substantial shock precursor due to CR pressure feedback and convert about 20-30% of the SN explosion energy into CRs. Since the high energy end of the CR proton spectrum is composed of the particles that are injected in the early stages, in order to predict nonthermal emissions, especially in X-ray and ${\gamma}-ray$ bands, it is important to follow the time dependent evolution of the shock dynamics, CR injection process, magnetic field amplification, and particle escape. Thus it is crucial to understand the details of these plasma interactions associated with collisionless shocks in successful modeling of nonlinear DSA.

• 대한기계학회논문집B
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• 제26권4호
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• pp.547-554
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• 2002

We are facing the serious environmental pollution difficulties such as acid rain, green house effects, etc. The gaseous matter NOx, SOx, VOCs which are regarded as main factors for these current pollutions are mainly emitted from power plants and vehicles. Therefore several leading countries are regulating the emissions strictly, especially the exhaust emissions from a Diesel engine without an aftertreatment device. The objective of this study is to find out soot and NO removal characteristics focused on the emissions of a Diesel engine by using nonthermal plasma for each engine speeds and loads. Electrostatic precipitator(wire-to-plate type reactor) is used for soot removal. Radicals generated from outer air and put into a mixing chamber in the end of exhaust line are used for NO removal. Concentration of exhaust emissions is analyzed from the gas analyzer(KaneMay) and FTIR to estimate by-products.

• 조명전기설비학회논문지
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• 제15권1호
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• pp.98-103
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• 2001

본 연구는 전기적 방법인 선대원통형 전극구조에서 발생되는 비열플라즈마를 이용하여 반응장치내에서의 NO의 제거율을 측정하고, 또 방전시의 방전 Image와 수평방향과 수직방향의 신호강도를 ICCD카메라를 이용하여 관측하였다. NO입자의 제거율은 NO농도가 낮을수록 높아지는 것을 확인할 수 있었으며, 수평방향의 신호강도와 수직방향의 신호강도는 NO농도가 낮을수록 큰 것을 확인할 수 있었다. 특히 방전에 의해 발생되는 비열플라즈마를 이용했을때의 교류방전시의 Image를 관측함으로써 NO입자의 방전 메카니즘을 보다 명확하게 규명하고자 하였다.