• 환경위생공학
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• 제16권3호
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• pp.72-79
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• 2001

The selective catalytic oxidation of toxic aromatic solvents (benzene, toluene, ethylbenzene, and styrene) and their mixtures were studied on a $Pt/{\;}{\gamma}-Al_2O_3$ catalyst at temperature ranging from $160~350^{\circ}C$. The deep conversion of aromatic solvents was increased as the inlet concentration was decreased and the reaction temperature was increased. The reactivity increases in order benzene > toluene > ethylbenzene > styrene. In mixture, remarkable effects on reaction rate and selectivity have been evidence ; the strongest inhibition effect is shown by styrene and increase in a reverse order with respect to that of reactivity. The inhibition effect was increased in order styrene > ethylbenzene > toluzene > benzene. This trend is due to the competition adsorption between the two or three reactants on the oxidized catalyst. Also, the deep conversion change of benzene was a small in tertiary mixtures(including of benzene and styrene) comparing with conversion characteristics of binary mixture with styrene. This result was due to small concentration of styrene. which had very strong inhibition effect.

• 대한인간공학회:학술대회논문집
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• 대한인간공학회 1997년도 추계학술대회논문집
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• pp.72-96
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• 1997

To investigate the difference of sweating reaction on somato types. We measured total sweat rate, locl sweat rate, skin temperature, physiological reactions and psyschological reactions at $25{\pm}1^{\circ}C$ and $25{\pm}1^{\circ}C$ under laboratory conditions. Nine healthy adult females were divided into three somato types (slender(3), normal(3) and obese type(3)). The results were as follows; Total sweat rate was highest in obese type, and then comes normal type and slender type in order. Local sweat rate was highest in infrascapular area, and then breast, the back of the hand, upperarm, ant. leg, and ant. thigh in order in all somato types. Mean skin temperature was highest in slender type, and then normal type and obese type in order. Rectal temperature, blood pressure and pulse rate were highest in boese type. Psychological reactions were appeared 'hot' 'humid' 'sweat' as ambient temperature go up. And somato types make little difference in psychological reactions.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2009년도 춘계학술대회 논문집
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• pp.888-888
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• 2009

A simulation study on SCR (Steam Carbon dioxide Reforming) process in gas-to-liquid (natural gas to Fischer-Tropsch synthetic fuel) process was carried out in order to find optimum reaction conditions for GTL (gas-to-liquid) process reaction. Optimum SCR operating conditions for synthesis gas to FT (Fischer-Tropsch) process were determined by changing reaction variables such as feed temperature and pressure. During the simulation, overall synthesis process was assumed to proceed under steady-state conditions. It was also assumed that physical properties of reaction medium were governed by RKS (Redlich-Kwong-Soave) equation. SCR process was considered as reaction models for synthesis gas in GTL proess. The effect of temperature and pressure on SCR process $H_2$/CO ratio and the effect of reaction pressure on SCR reaction were mainly examined. Simulation results were also compared to experimental results to confirm the reliability of simulation model. Simulation results were reasonably well matched with experimental results.

• 한국지하수토양환경학회지:지하수토양환경
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• 제10권4호
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• pp.62-69
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• 2005

본 연구에서는 천연 망간산화물에 의한 4-클로로페놀 화합물의 제거효과를 평가하였으며 자연유기물질과 용액의 pH에 의한 분해율 변화를 살펴보았다. 천연망간산화물은 4-클로로페놀 화합물의 제거에 효과적이었으며 실험결과의 분석을 통하여 반응계수 및 차수에 대한 정량적인 값을 도출하였다. 그 결과, 전체적인 반응은 2차반응으로서 4-클로로페놀 화합물에 대하여 1차, 망간산화물에 대하여 1차에 비례하는 반응이었다. 망간산화물에 의한 4-클로로페놀 화합물의 산화반응은 표면에서 일어나며 pH에 큰 영향을 받았다. 용액의 pH가 망간산화물의 영가전위(PZC) 값보다 클 경우 반응율은 급격히 감소하였으며 PZC 보다 pH가 작은 경우에도 반응율은 감소하였다. 휴믹산을 첨가한 경우 4-클로로페놀 화합물의 산회중합 반응은 다소 증가하는 경향을 보여 휴믹산이 중합반응에 관여하고 있다고 평가할 수 있다. 본 연구 결과, 경제적인 비용으로서 천연망간산화물을 이용하여 페놀계 오염물의 제거에 효과적으로 사용 할 수 있는 방안을 제시하였다.

• 국제지역연구
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• 제22권4호
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• pp.3-18
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• 2018

본 연구에서는 변동성반응가설에 입각한 T-GARCH 모형을 사용하여 최근 24년간의 일별 주식시장 수익률 자료를 바탕으로 OECD 29개 회원국들의 자본시장 충격반응도를 분석하였다. 연구모형에 사용한 독립변수로는 글로벌 금융위기의 진원지이며 세계시장 점유율도 가장 큰 미국시장 수익률을 사용하였다. 그 결과 OECD 회원국 중 미국으로부터의 수익률 전이효과가 가장 큰 나라는 프랑스, 핀란드, 멕시코의 순으로 나타났고 모형의 설명력은 캐나다, 멕시코, 프랑스 순으로 나타났다. 변동성반응가설에 입각한 충격반응의 크기로는 독일, 칠레, 스위스, 덴마크의 순으로 크게 나타났고 하락시장 충격에 대한 반응은 그리스, 영국, 호주, 일본의 순으로 크게 나타났다. NAFTA에 속한 캐나다와 멕시코는 예상대로 미국시장으로부터의 수익률 전이와 설명력이 크게 나타났으나 충격반응의 정도는 OECD 회원국들 중 하위권에 속하는 것으로 나타나 인근 지역의 국가들간의 더 큰 영향력이 존재한다는 중력이론을 지지하지 않았다. 한편, 2008년 미국발 글로벌 금융위기기간만을 고려한 소표본 분석을 통해서는 전체 기간과는 달리 북미 3국의 충격반응도가 서로 일관성이 없는 대신 유럽 각국의 충격반응도는 더욱 강하게 나타남으로써 미국발 충격이 주로 유럽지역에 미쳤음을 입증해 주었다.

• 대한화학회지
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• 제48권2호
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• pp.195-202
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• 2004

미셀 촉매 작용은 이론과 실험 화학 교과내용에서 중요한 부분이다. 산성 용액에서 도데실황산 나트륨(SDS)을 촉매로 한 글리신과 과망가니즈산 칼륨의 반응은 미셀 촉매 작용을 보여주는 반응속도론적 실험으로 적합하며, 고등학교와 대학 학부과정의 물리화학실험에서 사용할 수 있다. 본 연구에서는 이 반응이 계면활성제 존재하에서 반응속도가 빨라지는 것을 관찰하기 위하여 SDS를 넣지 않은 경우와 넣은 경우 모두 실험을 진행하였고, 얻어진 k를 [SDS]에 대하여 도시하였다. SDS의 임계 미셀 농도 이하에서부터 계면활성제에 의한 촉매 효과가 관찰되었는데, 이 선-미셀 촉매 효과는 양의 협동효과에 의한 것임을 알 수 있다. 얻어진 양의 협동지수(n)는 2.37이다. 또한 기질과 산화제의 농도에 따른 반응속도 변화도 논의하였다. 반응은 유사 일차 반응으로 진행되었으며, 글리신과 과망가니즈산 이온의 농도에 각각 일차 반응으로 나타나 전체 반응 차수는 이차 반응이었다. 반응 시간은 3~4시간으로 한 실험 시간에 몇 개의 실험 데이터를 얻을 수 있다. 용액 제조와 실험 과정에 대해서 자세히 기술하였으며, 또한 계면활성제에 의한 촉매 작용의 이론도 논의하였다.

• Bulletin of the Korean Chemical Society
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• 제35권6호
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• pp.1789-1793
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• 2014

Pseudo-first-order rate constants ($k_{obsd}$) have been measured spectrophotometrically for the reactions of 5-nitro-8-quinolyl nicotinate (4) and 5-nitro-8-quinolyl isonicotinate (5) with alkali metal ethoxides (EtOM; M = K, Na and Li) in anhydrous ethanol at $25.0{\pm}0.1^{\circ}C$. The plots of $k_{obsd}$ vs. [EtOM] curve slightly upward for the reactions with EtOK and EtONa but are linear for the reactions with EtOLi and for those with EtOK in the presence of 18-crown-6-ether. Dissection of $k_{obsd}$ into $k_{EtO^-}$ and $k_{EtOM}$ (i.e., the second-order rate constants for the reactions with the dissociated $EtO^-$ and ion-paired EtOM, respectively) has revealed that the reactivity increases in the order $EtO^-{\approx}EtOLi$ < EtOK < EtONa for the reactions of 4 and EtOLi < $EtO^-$ < EtOK < EtONa for the reactions of 5. Comparison of the kinetic results for the reactions of 4 and 5 with those reported previously for the corresponding reactions of 5-nitro-8-quinolyl benzoate (2) and picolinate (3) has revealed that the esters possessing a pyridine ring (i.e., 3-5) are significantly more reactive than the benzoate ester 2 due to the presence of the electronegative N atom (e.g., 2 << 3 < 4 < 5). It has been concluded that $M^+$ ion catalyzes the reactions of 3-5 by increasing the electrophilicity of the reaction center through a five-membered cyclic transition state (TS) for the reaction of 3 and via a four-membered cyclic TS for the reactions of 4 and 5.

• 한국광물학회지
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• 제11권1호
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• pp.20-31
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• 1998

Adsorption of metal elements onto illite and halloysite was investigated at $25^{\circ}C$ using pollutant water collected from the gold-bearing metal mine. Incipient solution of pH 3.19 was reacted with clay minerals as a function of time: 10 minute, 30 minute, 1 hour, 12 hour, 24 hour, 1 day, 2 day, 1 week, and 2 week. Twenty-seven cations and six anions from solutions were analyzed by AAs (atomic absorption spectrometer), ICP(induced-coupled plasma), and IC (ion chromatography). Speciation and saturation index of solutions were calculated by WATEQ4F and MINTEQA2 codes, indicating that most of metal ions exist as free ions and that there is little difference in chemical species and relative abundances between initial solution and reacted solutions. The adsorption results showed that the adsorption extent of elements varies depending on mineral types and reaction time. As for illite, adsorption after 1 hour-reaction occurs in the order of As>Pb>Ge>Li>Co, Pb, Cr, Ba>Cs for trace elements and Fe>K>Na>Mn>Al>Ca>Si for major elements, respectively. As for halloysite, adsorption after 1 hour-reaction occurs in the order of Cu>Pb>Li>Ge>Cr>Zn>As>Ba>Ti>Cd>Co for trace elements and Fe>K>Mn>Ca>Al>Na>Si for major elements, respectively. After 2 week-reaction, the adsorption occurs in the order of Cu>As>Zn>Li>Ge>Co>Ti>Ba>Ni>Pb>Cr>Cd>Se for trace elements and Fe>K>Mn>Al, Mg>Ca>Na, Si for major elements, respectively. No significant adsorption as well as selectivity was found for anions. Although halloysite has a 1:1 layer structure, its capacity of adsorption is greater than that of illite with 2:1 structure, probably due to its peculiar mineralogical characteristics. According to FTIR (Fourier transform infrared spectroscopy) results, there was no shift in the OH-stretching bond for illite, but the ν1 bond at 3695 cm-1 for halloysite was found to be stronger. In the viewpoint of adsorption, illite is characterized by an inner-sphere complex, whereas halloysite by an outer-sphere complex, respectively. Initial ion activity and dissociation constant of metal elements are regarded as the main factors that control the adsorption behaviors in a natural system containing multicomponents at the acidic condition.

• 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.

• Bulletin of the Korean Chemical Society
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• 제15권10호
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• pp.857-860
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• 1994

We have calculated the ${\pi}$-electron density, atom self-polarizability, and free valence on each atom of N-(2-chlorobenzyl)-pyridinium, N-(benzyl)-2-chloropyridinium, and N-(2-chlorobenzyl)-2-chloropyridinium salts using a simple Huckel method in order to discuss their intramolecular photocyclization reaction in a qualitative method. Our calculation qualitatively predicts that photocyclization occurs through forming radicals as a reaction intermediate by breaking a C-Cl bond after photoexcitation into a triplet state via intersystem crossing from an initially excited singlet state. We noticed that this C-Cl bond breaking is aided by ${\pi}$-complex formation between a chlorine atom and the ${\pi}$ -electrons of the neighboring ring in the triplet state and a stronger ${\pi}$-complex bond makes C-Cl bond breaking, i.e., radical formation, much easier. A chlorine atom will form a stronger ${\pi}$ -complex bond to a benzyl ring of N-(benzyl)-2-chloropyridinium than a pyridinium ring of N-(2-chlorobenzyl)-pyridinium because the former can donate its ${\pi}$-electron more easily than the latter. The chlorine at position 15 of N-(2-chlorobenzyl)-2-chloropyridinium salt in the excited state also provides its ${\pi}$-electron to the benzyl ring. So this ${\pi}$-electron can increase the bond strength of the $\pi-complex.$ Therefore, the strength of ${\pi}$-complex follows the order of N-(2-chlorobenzyl)-2-chloropyridinium, N-(benzyl)-2-chloropyridinium, and N-(2-chlorobenzyl)-pyridinium salts and thus the radical formation rate. This provides us with an intramolecular photocyclization reaction rate of the same order as given above.