• Applied Chemistry for Engineering
• /
• v.26 no.1
• /
• pp.67-73
• /
• 2015

Using a computational fluid dynamics technique, the flow characteristics and particle residence time in a Taylor reactor were studied. Since flow characteristics in a Taylor reactor are dependent on the operating conditions, effects of the inlet flow velocity and reactor rotational speed were investigated. In addition, the particle residence time of $LiNiMnCoO_2$ (NMC), which is a cathode material in lithium-ion battery, is estimated in the Taylor vortex flow (TVF) region. Without considering the complex chemical reaction at the inlet, the effect of Taylor flow was studied. The results show that the particle residence time increases as the rotating speed increased and the flow rate decreased.

• Journal of Soil and Groundwater Environment
• /
• v.11 no.6
• /
• pp.76-82
• /
• 2006

Fenton's reaction are difficult to apply in the field due to the low pH requirements for the reaction and the loss of reactivity caused by the precipitation of iron (II) at neutral pH. Moreover, Fenton-like reactions using iron mineral instead of injection of iron ion as a catalyst are operated to get high removal result at low pH. Because hydroxyl radical can generate at the surface of iron mineral, there are competition with a lot of hydroxide at around neutral pH. On the other side, to operate Fenton's reaction series at neutral pH, modified Fenton reaction is suggested. The complexes, composed by iron ions (ferrous ion or ferric ion)-chelating agent, could be acted as a catalyst and presented in the solution at neutral pH. However, modified Fenton reaction requires a lot of hydrogen peroxide. Accordingly, the purpose of this experiment was to effectively combine Fenton-like reaction and modified Fenton reaction for extending application of Fenton's reaction. i.e., injecting chelating agents in Fenton-like reaction at around neutral pH is increasing the concentration of dissolved iron ion and highly promoting the oxidation effect. 2,4,6-trinitrotoluene (TNT) was used as a probe compound for comparing reaction efficiencies in this study. If the concentration of dissolved iron ion in combined Fenton process were existed more than 0.1 mM, the total TNT removal were increased. Magnetite-NTA system showed the best TNT removal (76%) and Magnetite-EDTA system indicated about 56% of TNT removal. The results of these experiments proved more promoted 40-60% of TNT removal than Fenton-like reaction's.

• Journal of Korean Society of Environmental Engineers
• /
• v.27 no.3
• /
• pp.253-261
• /
• 2005

Catalytic wet oxidation of ppm levels of trichloroethylene (TCE) in water has been conducted using $TiO_2$-supported cobalt oxides at a given temperature and weight hourly space velocity. 5% $CoO_x/TiO_2$ might be the most promising catalyst for the wet oxidation at $36^{\circ}C$ although it exhibited a transient behavior in time on-stream activity. Not only could the bare support be inactive for the wet decomposition reaction, but no TCE removal also occurred by the process of adsorption on $TiO_2$ surface. The catalytic activity was independent of all particle sizes used, thereby representing no mass transfer limitation in intraparticle diffusion. Characterization of the $CoO_x$ catalyst by acquiring XPS spectra of both fresh and used Co surfaces gave different surface spectral features of each $CoO_x$. Co $2p_{3/2}$ binding energy of Co species exposed predominantly onto the outermost surface of the fresh catalyst appeared at 781.3 eV, which is very similar to the chemical states of $CoTiO_x$ such as $Co_2TiO_4$ and $CoTiO_3$. The spent catalyst possessed a 780.3 eV main peak with a satellite structure at 795.8 eV. Based on XPS spectra of reference Co compound, the TCE-exposed Co surfaces could be assigned to be in the form of mainly $Co_3O_4$. XRD measurements indicated that the phase structure of Co species in 5% $CoO_x/TiO_2$ catalyst even before reaction is quite comparable to the diffraction lines of external $Co_3O_4$ standard. A model structure of $CoO_x$ present on titania surfaces would be $Co_3O_4$, encapsulated in thin-film $CoTiO_x$ species consisting of $Co_2TiO_4$ and $CoTiO_3$, which may be active for the decomposition of TCE in a flow of water.

• Korean Journal of Cognitive Science
• /
• v.27 no.3
• /
• pp.441-467
• /
• 2016

This fMRI study is aim to investigate effects of competitive environment in cognitive empathic process in human brain. Empathy is known as a crucial factor for human's adaptive behavior in aspects of social cognition and it is almost automatic process, on the other hand competitive situation is psychologically devastated environment to win someone for getting rewards. We hypnotized that reading and understanding of other person's mind are a specific characteristic related to survival evolutionarily, however competition would have an effect on the empathic cognitive process because of mechanisms of competition. To manipulate the competitive atmosphere, one researcher took a role of competitor against participants and they were instructed to get monetary rewards when their performance was better than a competitor. 21 participants(9 males and 12 females) performed to judge the emotional valence of the empathic task consisted of illustrated images with various situation could be experienced in real world as on $1^{st}$ person perspective in both competitive and non-competitive condition, and did same performance with objects stimulus in control condition. In order to examine the competition effects on empathic process,, hemodynamic response were obtained during fMRI session and the imaging data were analyzed to identify brain regions where responses to each condition across the two consecutive runs. Participants' reaction time in competitive condition was faster statistically significant than non-competitive one. Activation for competitive condition increased in the following areas: ACC, mPFC, SMG, thalamus extended caudate and Nacc, parahippocampal gyrus, and for non-competitive condition increased paracingulate gyrus, temporal pole, vmPFC, superior occipital gyrus. As a result of regression analysis using empathic scores as covariance, the rSMG, IFG, fusiform gyrus, thalamus, putamen were correlated with higher empathic levels, and TPJ were correlated with lower empathic scores. We suggest that these observations could mean competitive environment have an effect on neural base of cognitive empathic process.

• Microbiology and Biotechnology Letters
• /
• v.26 no.1
• /
• pp.1-6
• /
• 1998

The characteristics of $CO_2$ fixation by Chlorella HA-1 cultured in bubble columns were studied to achieve high photosynthetic rates per basal area. The influence of experimental conditions such as the diameter of a bubble column and gas flow rate, on photosynthesis of Chlorella HA-1 was investigated. The maximum productivity and the overall $CO_2$ fixation rate obtained in a 0.15 L bubble column was 1.09 g dry biomassa-day and 1048 g CO$_2/\m^2$-day, respectively. Light limitation has been observed in the bubble columns having a diameter larger than 3.5 cm.. As the reactor volume increased, the decrease of the $CO_2$ fixation rate was remarkable. High gas flow rate was helpful to mitigate the light limitation problem.

• Journal of the korean academy of Pediatric Dentistry
• /
• v.44 no.3
• /
• pp.365-369
• /
• 2017

Local anesthetics are widely used in clinical dentistry. However, while rare, there have been some reports of true hypersensitivity to local anesthetics. A case of hypersensitivity in a 26-month-old boy is reported. After administering local anesthesia with lidocaine, treatment was performed while the patient was under oral sedation. After treatment, the patient presented with lower lip edema. Treatment with anti-histamines and a steroid successfully reversed his symptoms.

• Proceedings of the Korean Nuclear Society Conference
• /
• 1995.10a
• /
• pp.55-60
• /
• 1995

CANDU형 원자로의 노심해석을 위해 핵연료 격자 및 반응도 설비(reactivity devices)에 대한 2군 군정수가 필요하다. 특히 CANDU형 원자로의 노심해석에 있어서 반응도 설비나 구조물은 증분격자 상수(Incremental Cross Section)에 의해 묘사된다. 현재 CANDU형 원자로의 반응도 설비의 증분격자 상수를 계산하기 위해 MULTICELL 코드를 사용하여 계산하고 있다. 그러나 weak absorber에 대해 기존의 증분격자 상수를 이용하여 계산한 반응도가는 시운전(Phase-B)조건에서의 노물리 시험치보다 다소 과소평가하고 있다. 본 연구에서는 증분격자 상수 계산 방법의 개선 방향을 모색하기 위해 SHETAN 및 MCNP 코드로 단일 격자에서의 반응도가를 계산하여 비교, 평가하였다. HCNP 계산의 결과는 조정봉(Adjuster rods)과 흡수봉/정지봉 (Mechanical Control Absorber/Shutoff rod)은 MULTICELL의 계산 결과보다 적으며, 경수영역 조절기(Liquid Zone Controller)는 크게 나타났다. 또한 SHETAN 코드를 이용한 결과는 MULTICELL의 결과보다 약간 크게 나타났다.

• Journal of the Korean Society of Clothing and Textiles
• /
• v.25 no.10
• /
• pp.1738-1744
• /
• 2001

본연구의 목적은 반응성 염료를 이용한 텐셀섬유의 피브릴화 조절 효과를 표면 형태, 감량율, 역학적 성질 및 태의 변화의 측면에서 고찰하는데 있다. 반응성 염료에 의한 가교는 섬유의 비결정 영역의 구조를 변화시켜 피브릴화를 억제하였으며 또한 효소의 작용에 영향을 주어 감량율을 감소시켰다. 반응성 염료에 의한 가교는 역학적 성질 중 특히 전단강성, 압축에너지, 압축레질리언스를 증가시켰다. 염색후 효소처리한 시료는 다른 시료보다 numeri와 fukurami 값이 높아 더 나은 종합태를 보였다. 공정순서에 따라 약간씩 차이가 있는 촉감을 나타냈다.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2012.08a
• /
• pp.334-334
• /
• 2012

태양전지 기술은 우주 항공에서부터 핸드폰과 같은 소규모 가전 시설에까지 폭 넓게 사용되고 있다. 현재 태양전지 기술은 기존의 화석 에너지에 비해 효율 측면에서의 열세함으로 인해 변환 효율을 높이는 연구가 진행되고 있다. 태양전지의 기본 구조에서 고반사막을 대신하여 선택적 투과막을 채용하면 적외선 영역은 광흡수층으로 재반사시키고 가시광선 영역은 선택적으로 투과시킬 수 있기 때문에 태양전지의 변환 효율을 높임과 동시에 채광에 유리한 투명 태양전지를 얻을 수 있다. 본 연구에서는 반응성 분위기에서 AlTi 단일 타겟을 스퍼터링하여 유리 기판 위에 AlTiO 선택적 투과막을 형성하고 광학적 특성을 평가하였다. 기존의 연구에서 스퍼터링으로 형성한 AlTiO 선택적 투과막은 가시광선 영역에서 약 30%의 비교적 높은 반사율을 나타내었다. 이번 연구에서는 광학 두께를 조절함으로써 가시광선 영역에서 반사율이 평균 20% 이상 감소하고 적외선 영역에서 약 30% 이상의 반사율을 나타내는 선택적 투과막을 형성한 결과를 보고한다.

• The Proceeding of the Korean Institute of Electromagnetic Engineering and Science
• /
• v.4 no.2
• /
• pp.82-90
• /
• 1993

전자파에 의한 산란현상의 해석은 지금까지 주로 시간조화함수의 형태를 지닌 전원에 의한 정 상상태의 산란에 관하여 이루어졌다. 그러나 레이다나 피파괴 검사, 전송선로 점검 등의 응용에서는 주로 펄스형태의 전자파를 사용하며, 따라서 시간에 따라 변화하는 함수형태의 전원에 의한 전자파의 산란해 석이 중요한 문제로 등장하였다. 또한 통신선로에서 외부의 잡음에 대한 혼신 등을 해석하거나, 낙뢰가 송 전선로에 미치는 영향을 해석하는 데에도 펄스신호의 산란해석이 필수적이다. 일반적인 함수의 형태를 지닌 전원에 의한 산란현상을 해석하기 위해서는 전원함수를 Fourier 변환하 여 주파수 영역의 스펙트럼을 구하고, 주파수영역에서의 산란해를 이용하여 Fourier 역변환을 하여 시간 영역의 해를 구할 수 있다. 주파수 영역에서의 산란판의 해를 Fourier 역변환 하기 위해서는 적분을 행하여야 하며, 일반적으로 적분과정에서 매우 복잡한 계산이 필요하고, 산란체의 구조가 복잡하여 해석 적인 해를 구할수 없는 경우에는 해석적으로 시간영역의 해를 구하는 것이 불가능하다. 시변 함수에 의 한 산란파를 구하기 위한 수치해석적 방법으로는 모멘트방법이나 유한요소법(Finite Element Method), 경계요소법(Boundary Element Method), 유한차분법(Finite Difference Method)등이 있으며, 해석적 해 를구할 수 없는 경우에 적용할 수 있는 반면에 많은 계산량이 요구된다.