• 한국수산과학회지
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• 제16권4호
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• pp.349-354
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• 1983

송풍식건조에 의한 어육건조중의 변색에 미치는 공기의 상대습도의 영향을 검토한 결과를 요약하면 다음과 같다. $40^{\circ}C,\;55^{\circ}C$ 및 $70^{\circ}C$에서의 어육건조중 어육변색의 주된 원인은 지방산화였다. 지방함량이 높은 어육일수록 지방산화에 의한 변색이 심하였다. $40^{\circ}C$와 $55^{\circ}C$에서의 건조중에는 공기의 상대습도가 $30\%$ 정도일 때 지방산화가 가장 늦었으며, 상대습도가 $30\%$ 보다 낮아지거나 높아질수록 지방산화가 촉진되었다. $70^{\circ}C$에서의 건조중에는 상대습도의 지방산화에 대한 뚜렷한 영향이 확인되지 않았으며, 고온에서는 지방산화가 조조온도에 민감한 듯 하였다. Maillard반응에 의한 갈변은 건조중의 변색에는 큰 영향을 미치지 않았고, 상대습도 $10\%{\sim}50\%$의 범위에서는 상대습도가 높을수록 반응속도가 빨랐다.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 1996년도 제23회 학술대회
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• pp.1-3
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• 1996

The characteristics of fretting wear are reviewed. Fretting damage depends on slip amplitude and classified into three groups: (1) an annular damage according to Mindlin's analysis at microslip region, (2) strong adhesive deformation without loose wear particles at the intermediate region, and (3) formation of fine oxide particles at the gross slip region. The critical slip amplitude of fretting is the boundary between (2) and (3). The boundary slip amplitude depends on normal load. The wear rate increases and saturates with increasing slip amplitude. But it is constant by considering the critical amplitude. The role of oxide particles are discussed. Three different actions are noted: accelerating wear, preventing wear and insignificant effect. The oxide shows two opposing effect depends on normal load and slip amplitude. This is related to the removal rate from the interface (abrasive action) and compaction rate at the interface to form a protective layer. The effect of oxidation is significant to determine the wear and friction. The diffusion of oxygen is restricted at the small amplitude. As a result, crack formation at the boundary is a predominant damage, related to fretting fatigue damage.

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2005년도 총회 및 춘계학술발표회
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• pp.49-52
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• 2005

In this study, abiotic transformation of 1-naphthol via oxidative-coupling reaction was evaluated using Mn oxide which is ubiquitous in natural soils. The transformation of 1-naphthol catalyzed by synthetic birnessite $({\delta}-MnO_2)$ followed pseudo-lst order reaction, and the rate constants was in the range of $0.053{\sim}0.13\;min^{-1}$ with birnessite loadings of $12.5{\sim}50\;mg/20\;mL$. Since the oxidation of 1-naphthol was occurred on the reactive surface of the oxide particles, the rate constants with various birnessite loadings were correlated with birnessite surface area concentration. The correlation showed a strong linearity, which confirms the supposition of the surface reaction. From the correlation, therefore, the surface area normalized rate constant, $k_{surf}$, was determined to be 0.032 $L/m^2\;min$.

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2003년도 총회 및 춘계학술발표회
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• pp.145-148
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• 2003

The batch experiments showed that 0.515mM 4-chlorophenol and its oxidation intermediates could be totally decomposed within 60 minutes by 1g/L steelers' dust and 0.485mM hydrogen peroxide at pH 2.7. The rate constants in the simplified kinetic model proposed in this study were estimated by fitting to the experimental data obtained in $H_2O$$_2$/steelers' dust system. Using the estimated kinetic rate constants, the simulation of 4-chlorophenol, ferrous iron, hydrogen peroxide, and hydroxyl radical concentration was performed. The predicted concentrations of 4-chlorophenol and hydrogen peroxide corresponded to the actual concentrations.

• 한국자동차공학회논문집
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• 제20권5호
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• pp.71-80
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• 2012

To improve the $NO_X$ conversion over a SCR (selective catalytic reduction) catalyst, the DOC (diesel oxidation catalyst) is usually placed upstream of the SCR catalyst to enhance the fast SCR reaction ($4NH_3+2NO+2NO_2{\rightarrow}4N_2+6H_2O$) using equimolar amounts of NO and $NO_2$. Here, a ratio of $NO_2/NO_X$ above 50% should be avoided, because the reaction with $NO_2$ only ($4NH_3+4NO+O_2{\rightarrow}4N_2+6H_2O$) is slower than the standard SCR reaction ($4NH_3+4NO+O_2{\rightarrow}4N_2+6H_2O$). In order to accurately predict the performance characteristics of SCR catalysts, it is therefore desired to develop a more simple and reliable mathematical and kinetic models on the oxidation kinetics of nitric oxide over a DOC. In the present work, the prediction accuracy and limit of three different chemical reaction kinetics models are presented to describe the chemicophysical characteristics and conversion performance of DOCs. Steady-state experiments with DOCs mounted on a light-duty four-cylinder 2.0-L turbocharged diesel engine then are performed, using an engine-dynamometer system to calibrate the kinetic parameters such as activation energies and preexponential factors of heterogeneous reactions. The reaction kinetics for NO oxidation over Pt-based catalysts is determined in conjunction with a transient one-dimensional (1D) heterogeneous plug flow reactor (PFR) model with diesel exhaust gas temperatures in the range of 115~$525^{\circ}C$ and space velocities in the range of $(0.4{\sim}6.5){\times}10^5\;h^{-1}$.

• Journal of Photoscience
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• 제11권2호
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• pp.77-81
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• 2004

Deoxygadusol (DO) and structurally related mycosporine-like amino acids, i.e. mycosporine glycine (MO) and mycosporine taurine (MT), were isolated from phytoplankton Prorocentrum micans and studied for the reactivity toward singlet oxygen. These water-soluble compounds with a cyclohexenone chromophore were all shown to be highly effective in quenching singlet oxygen ($^1$ $O_2$), with the efficiencies being significantly larger compared with histidine, a well-known $^1$ $O_2$ quencher. The $^1$ $O_2$ reaction rate constant ( $k_{Q}$) of DG was determined to be 5.4 ${\times}$ 10$^{7}$ $M^{-1}$ $s^{-1}$ by a steady state method based on competitive inhibition of rubrene oxidation. The feasibility of this method was confirmed by estimating the $k_{Q}$ values for MG and two other quenchers, furfuryl alcohol and 1,4-diazabicyclo [2,2,2]octane, and comparing with those values determined by the time-resolved $^1$ $O_2$ decay method in the previous work.ork.

• 대한토목학회논문집
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• 제26권4B호
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• pp.421-426
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• 2006

본 연구는 생물학적 질산화 공정에서 암모늄 이온과 활성을 가진 질산화균의 초기 농도가 질산화에 미치는 영향을 확인하고, 이에 따른 동역학식을 제시하고자 하였다. 먼저 실험에 이용된 슬러지의 질산화균 농도는 미생물 호흡률 실험으로 측정하였는데, 배양된 슬러지 중 42.8%가 활성을 가진 질산화균으로 나타났다. 암모늄 이온과 질산화균의 초기 농도를 달리하여 $N_0/X_0$비가 0.025~0.493의 조건에서 잘산화 실험을 실시하였으며, 이를 통해 암모늄 이온과 질산화균의 농도가 상이하더라도 $N_0/X_0$ 비가 동일할 경우 암모늄 산화율이 동일함을 확인하였다. 또한 $N_0/X_0$ 비와 비기질이용율의 관계는 Contois 형태의 관계식으로 표현되었으며, 최대 비암모늄산화율($q_{Nmax}$)은 4.32 gN/gVSS/day, 반 포화속도 상수($K_N{^{\prime}}$)는 0,013 gN/gVSS인 것으로 확인되었다.

• 한국물환경학회지
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• 제20권5호
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• pp.488-493
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• 2004

The effects were examined from several conditions of $TiO_2$ photocatalysis reaction to phenols degradation by changing it's reacting conditions such as phenol concentration, pH, $TiO_2$ concentration, $H_2O_2$ concentration, flow rate, and intensity of ultraviolet rays. Phenol degradation was more efficient in low concentration of phenol, neutral pH. Phenol degradation appeared to increase as concentration of $TiO_2$ photocatalyst, that of $H_2O_2$ and intensity of ultraviolet rays increased. As $TiO_2$ dosage increased, initial rate constant k linearly increased. When $H_2O_2$ was injected more than optimum, phenol removal rate didn't increase in proportional to the change of $H_2O_2$ concentration as OH radicals was being consumed. When flow rate is less than $4.75m^3/m^2$ day, phenol removal efficiency appeared to decrease as ultraviolet rays transmission rate becomes low by $TiO_2$ suspension coated in photo reaction column. Meanwhile, initial rate constant according to light intensity change in less than $25mW/cm^2$ appeared to be in proportion to light intensity ($mW/cm^2$) Removal efficiency decreased about 12% after 180 minutes of reaction time while showed stable removal efficiency of 100% after 300 minutes when using regenerated $TiO_2$.

• 한국전기전자재료학회논문지
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• 제22권1호
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• pp.41-46
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• 2009

The low dielectric SiOCH films were deposited on p-type Si(100) substrates through the dissociation of BTMSM $(((CH_3)_3Si)_2CH_2)$ precursors with oxygen gas by using PECVD method. BTMSM precursor was introduced with the flow rates from 42 to 60 sccm by 2 sccm step into reaction chamber but with the constant flow rate of 60 sccm $O_2$. SiOCH thin films were annealed at $450^{\circ}C$ for 30 minutes. The electrical property of SiOCH thin films was studied by MIS, Al/SiOCH/p-Si(100), structure. Annealed samples showed large reduction of the maximum capacitance yielding low dielectric constant owing to reductions of surface charge density. After exposure at room temperature and atmospheric pressure, dielectric constant of SiOCH films was totally increased. However, annealed SiOCH thin films were more stable than as-deposited SiOCH thin films for natural oxidation.

• 대한화학회지
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• 제53권6호
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• pp.709-716
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• 2009

일정한 이온 세기의 알칼리 용액에서 과망간산에 의한 프포독심 프록세틸(Cefpodoxime Proxetil) 의 산화의 속도론적 경로가 분광광도법적으로 연구되었다. 그 반응은 과망간산 이온 농도에서 일차 속도론적으로 나타났으며, 프포독심 산과 알칼리 농도에서 단일 이하의 차수를 나타내었다. 용매의 이온 세기가 증가함에 따라 속도도 증가하였다. 산화 반응은 프포독심 산과 함께 복합체를 형성하는 알칼리-과망간산 종들을 통하여 진행된다. 반응물을 만들기 위해서 프포독심 산의 자유 라디칼과 과망간산의 다른 분자 사이의 빠른 반응에 이어서 다음 분해가 천천히 진행된다. 다양한 온도에서 반응의 조사는 제안하는 메커니즘의 느린 단계를 고려한 활성화 변수들의 결정할 수 있게 하고 일차 속도론을 따른다. 제안하는 메커니즘과 유도된 속도 법칙들은 관찰된 속도들과 일치하였다.