• Transactions of the Korean hydrogen and new energy society
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• v.34 no.1
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• pp.69-76
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• 2023

An experimental study was conducted on a 4-stroke direct injection diesel engine to examine the combustion and emission characteristics of 1-octanol/diesel fuel blends. The concentration of 1-octanol in the fuel blends was 10%, 30%, and 50% by volume. Experiments were conducted by varying the engine torque from 6 Nm to 12 Nm at the same engine speed of 2,700 rpm. Results showed that the fuel conversion efficiency increased as the 1-octanol proportion increased under most experimental conditions. However, the brake specific fuel consumption increased due to the relatively low lower heating value of 1-octanol. The smoke opacity and the concentrations of NO_x and CO emissions generally decreased with brake mean effective pressure as the 1-octanol proportion increased. On the other hand, the unburned hydrocarbon concentration increased with an ascending ratio of 1-octanol.

• Applied Biological Chemistry
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• v.40 no.1
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• pp.71-75
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• 1997

Important physicochemical properties of captafol [N-(1,1,2,2-tetrachloro-ethylthio)cyclohex-4-ene-1,2-dicarboximide], water solubility, vapor pressure, hydrolysis and octanol/water partition coefficient(Kow) were measured based on the standard EPA and OECD methods. Water solubility of the chemical was 2.24 ppm at $25^{\circ}C$. Half-life by hydrolysis at $25^{\circ}C$ in the buffer solution of pH 3.0, pH 7.0, and pH 8.0 was 77.8 hr, 6.54 hr and 0.72 hr, respectively, demonstrating instability in alkaline solution. The half-life in acid condition was not significantly different by temperature change, however, that in neutral or alkaline solution became shorter at $40^{\circ}C$. Hydrolysis study with a reference compound, diazinon, proved that the experimental method of the present study is reliable. Vapor pressure of captafol, $8.27{\times}10^{-9}$ torr at $20^{\circ}C$, was calculated from the equation, log P=6.94-(4401.6/T) plotted on the experiment results under different temperature conditions, 40, 50, and $60^{\circ}C$. pressure of captafol, the contamination of captafol would not happen easily in environment by vaporization. High Kow value of 1,523 was observed and this might result in bioconcentration through food chain when captafol was exposed. However, affecting human health through aquatic bioaccumulation is not likely to occur due to its rapid hydrolysis in the environment.

• Analytical Science and Technology
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• v.6 no.1
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• pp.1-8
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• 1993

The purpose of this study is to investigate the elution behavior of monosubstituted phenols and benzenes in micellar liquid chromatographic system, $C_{18}$ column-anionic surfactant, sodium dodecyl sulfate(SDS). The partition coefficients between the micellar pseudophase-water and modified stationary phase-water are calculated by the relationship between solute retention and micellar mobile phase(SDS) composition. The free energy of transfer of solute from water to micelle is also calculated from these values. There is a direct correlation between the hydrophobicity parameters in MLC and corresponding partition data for 1-octanol-water, which indicates that the hydrophobicity of molecules plays an important role in the partition for both systems and that quantitative structure activity relationships(QSAR) are available from studies on micellar partition. The other purpose of this study is to investigate methylene selectivity of alkyl homologous series through correlation between retention and the number of carbons. The correlation between hydrophobicity parameters in MLC and 1-octanol-water partition data was also observed when n-propanol was as a modifier in the mobile phase.

• Applied Biological Chemistry
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• v.40 no.1
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• pp.76-79
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• 1997

Several physicochemical properties such as water solubility, vapor pressure, hydrolysis and octanol/water partition coefficient(Kow) of flupyrazofos, the first organophosphorus insecticide developed in Korea, were measured based on EPA and OECD methods. Water solubility was low showing 0.80 ppm at $25^{\circ}C$ and in hydrolysis study, half-life at $25^{\circ}C$ was 266.5 hr(pH 4.0), 180.0 hr(pH 7.0) and 120.9 hr(pH 9.0) demonstrating instability in alkaline solution. At $40^{\circ}C$ hydrolysis rate was $2{\sim}4$ times higher than that at $25^{\circ}C$. The equation log P=0.673-(1565.4/T) was obtained from vapor pressure experiments at three different temperatures (25, 35, $45^{\circ}C$) and $2.81{\times}10^{-5}$ torr was obtained at $25^{\circ}C$. This value is similar to that of diazinon and 1,000 times lower than that of DDVP suggesting it would not give environmental contamination by volatilization. High log Kow(5.24) was observed and this might result in bioconcentration through food chain. However, its possibility is not likely to be high due to its relatively rapid hydrolysis.

• Transactions of the Korean hydrogen and new energy society
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• v.34 no.6
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• pp.767-772
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• 2023

In this study, combustion experiments were conducted at various engine speeds under full-load conditions using a single-cylinder diesel engine by blending butanol, pentanol, and octanol with diesel at a volume ratio of 10%. Experimental results revealed that higher alcohol-diesel blends resulted in lower brake torque and brake power than pure diesel due to the lower calorific value and the cooling effect during evaporation. An evident improvement in the brake thermal efficiency of the blended fuels was observed at engine speeds below 2,000 rpm, with the butanol blend exhibiting the highest thermal efficiency overall. Furthermore, the brake-specific fuel consumption of the higher alcohol-diesel blends was lower than that of pure diesel at speeds below 2,200 rpm. When using blended fuels, the exhaust gas temperature decreased under lean mixture conditions due to heat loss to the air and the cooling effect from fuel evaporation.

• Analytical Science and Technology
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• v.9 no.1
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• pp.91-97
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• 1996

The extent of binding($K_B$) between chemical compound and humic acid was measured as an indicator of decrease in toxicity. From the experimental $K_B$ and estimated $K_B$ calculated from $K_{ow}$, no reduction of toxicity among test chemicals in aquatic systems were predicted except P,P'-DDT. The effect of humic acid on aquatic organisms is not expected to be significant for the compounds with $K_B{\leq}10^5$ or $K_{ow}{\leq}10^6$.

• Environmental Analysis Health and Toxicology
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• v.20 no.4 s.51
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• pp.351-358
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• 2005

The n -octanol/water partition coefficient (Pow) is one of the most important parameters employed for estimating a chemiral's environmental fate and toxicity. The shake-flask method, one direct experimental method, i.1 prone to experimental artifacts for highly hydrophobic compounds. Thus, a valid method for direct determination of the Pow of highly hydrophobic compounds is needed. The slow -stirring method has been demonstrated to provide reliable log Pow data to log Pow greater than 5. This study was performed to evaluate the accuracy of slow- stirring experiment for determination of log Pow, particularly for highly hydrophobic compounds. 1, 2, 3, 4-tetrachlorobenzene, hexachlorobezene, 2, 2', 3, 3', 5, 5', 6, 6'-octachlorobiphenyl, decachlorobiphenyl, and p, p'-DDT (4.5$\times$0.02, 5.41$\times$0.06, 7.26$\times$0.04, 7.87$\times$0.10, and 6.03$\times$0.06, respectively. The octanol/water partition coefficient by the slow-stirring method were very similar to the literature values. These results indicate that the slow- stirring method allows for reliable determination of log Pow of highly hydrophobic chemicals.

• Proceedings of the Korea Water Resources Association Conference
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• 2020.06a
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• pp.148-148
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• 2020

산업의 고도화가 진행됨에 따라 화학원료의 사용이 증가하고 있고 독성을 가진 화학물질이 하천으로 유입되는 사고가 빈번하게 발생하고 있다. 수환경으로 유입되는 유해화학물질은 주로 무색무취의 물질들로 사고가 발생하더라도 초기 발견이 어려워 어류폐사를 유발하거나 취수시설에서 용수로 취수되는 경우가 발생하기 때문에 이에 대한 대응책 마련이 필수적이다. 하천에 유입된 오염물질의 거동을 신속하게 예측하기 위해 1차원 오염물질 추적 모형이 활용되는데, Fickian 이송-분산 모형(Fickian Advection-dispersion equation model; FADE)이 주로 사용되고 있다. 하지만 FADE는 오염물질이 하천 저장대에서 지체되는 현상을 반영하지 못하기 때문에 농도곡선의 왜곡도를 구현하지 못하는 단점을 가지고 있다. 따라서 본 연구에서는 하천저장대모형(River Storage Model; RSM)을 개발하고 이를 국가하천인 감천에 적용하였다. 본 연구에서 개발한 RSM은 분산계수, 본류대 면적, 저장대 면적, 저장대 교환계수의 네 가지 매개변수를 통해서 하천의 물질 저장 및 교환 특성를 구현한 non-Fickian 모형으로서, 생화학반응, 휘발, 흡·탈착항을 추가하여 유해화학물질의 혼합 거동을 정확하게 모의할 수 있도록 개발하였다. 저장대 모형의 매개변수를 산정하기 위해서 하천 유량과 지형자료를 기반으로 HEC-RAS를 모의하여 계산된 수리특성을 입력변수로 사용하였다. 저수기, 평수기, 풍수기 유량을 기준으로 세 경우의 시나리오 모의를 수행하였는데, 5ton의 톨루엔이 김천산업단지에서 감천으로 유입된 경우 약 20km 하류에 위치한 취수장에서 톨루엔의 농도변화를 예측했다. 보존성 물질에 대한 모의 결과, 풍수기의 경우 저수기에 비해 유속이 크기 때문에 취수장에서 20.56시간 먼저 기준농도에 도달하고, 7.21시간 더 짧게 머무는 것으로 나타났다. 유해화학물질의 반응특성에 대한 민감도 분석을 시행한 결과, 생화학적 반감기가 18.98시간보다 길고, 옥탄올-물 분배계수가 2.267 이하인 물질은 생분해 및 흡·탈착 반응에 둔감한 것으로 나타났다. 1m 수심 기준 0.114m/s 이하 유속에서의 하천 수리조건에서는 화학물질의 휘발성을 무시할 수 있는 것으로 밝혀졌다.

• Korean Chemical Engineering Research
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• v.57 no.6
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• pp.790-803
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• 2019

The dioctyl terephthalic acid (DOTP) process produces plastic plasticizers by esterification of terephthalic acid with powder in the form of octanol. In this study, the dust explosion characteristics of terephthalic acid directly injected into the manhole in the form of powder in the presence of flammable solvent or vapor in the reactor of this process were investigated. Dust particle size and particle size distribution dust characteristics were investigated, and pyrolysis characteristics of dust were investigated to estimate fire and explosion characteristics and ignition temperature. Also, the minimum ignition energy experiment was performed to evaluate the explosion sensitivity. As a result, the average particle size of terephthalic acid powder was $143.433{\mu}m$. From the thermal analysis carried out under these particle size and particle size distribution conditions, the ignition temperature of the dust was about $253^{\circ}C$. The lower explosive limit (LEL) of the terephthalic acid was determined to be $50g/m^3$. The minimum ignition energy (MIE) for explosion sensitivity is (10 < MIE < 300) mJ, and the estimated minimum ignition energy (Es) based on the ignition probability is 210 mJ. The maximum explosion pressure ($P_{max}$) and the maximum explosion pressure rise rate $({\frac{dP}{dt}})_{max}$ of terephthalic acid dust were 7.1 bar and 511 bar/s, respectively. The dust explosion index (Kst) was 139 mbar/s, corresponding to the dust explosion grade St 1.

• Journal of dental hygiene science
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• v.2 no.1
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• pp.47-51
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• 2002

The concentration of intracellular $Ca^{2+}$ was measured by spectrofluorometer after rat submandibular acinar cells were loaded with fura-2/AM(fura-2). After isoproterenol and octanol were administered while letting submandibular gland acinar cell placed in a perfusion chamber flow through a standard solution, the changes of $Ca^{2+}$ concentration were measured. When they were administered separately, there showed little changes of intracellular $Ca^{2+}$ concentration. When they were administered at the same time, however the concentration of intracellar $Ca^{2+}$ was shown to increase. When forskolin, an adenylate cyclase activater, was administerd together with octanol the response looked similar to the response of isoproterenol. In case of the extracellular $Ca^{2+}$ was removed by omitting $Ca^{2+}$ in standard solution and treating EGTA, isoproterenol and forskolin does not affect to the concentration of intracellular $Ca^{2+}$. Therefore, it was certified that the increase of intracellular $Ca^{2+}$ was caused from outside the cell. In order to know that the $Ca^{2+}$ influx is related with capacitative entry pathway, godolinium, blocker of that pathway was treated. With the result of that experiment there was no complete control of the increase in the concentration of intracellular $Ca^{2+}$. However, speed and amount of $Ca^{2+}$ increase was comparatively diminished.