• 한국전산유체공학회지
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• 제21권1호
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• pp.43-49
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• 2016

Thermal cracking is commonly modeled as plug flow reaction, neglecting the lateral gradients present. In this paper, 2-dimensional computational fluid dynamics including turbulence model and molecular reaction scheme are carried out. This simulation is solved by means of coupled implicit scheme for stable convergence of solution. The reactor is modeled as an isothermal tube, whose length is 1.2 m and radius is 0.01 m, respectively. At first, The radial profile of velocity and temperature at each point are predicted in its condition. Then the bulk temperature and conversion curve along the axial direction are compared with other published data to identify the reason why discussed variations of properties are important to product yield. Finally, defining a new non-dimensional number, Effect of interaction with turbulence, heat transfer and chemical reaction are discussed for design of thermal cracking furnace.

• 한국염색가공학회지
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• 제24권1호
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• pp.39-44
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• 2012

To improve flame retardation of poly(ethylene terephthalate) (PET) against burning, resorcinol bis(diphenyl phosphate) (RDP), phosphorous containing flame retardant, was incorporated into PET backbone by radical reaction pathway. Radical endcapping of PET with RDP was confirmed by spectroscopic and thermal analysis. From 400 MHz $^{31}P$ solid state FT-NMR spectrum of PET with RDP (PET-RDP), phosphorus spectra peak in RDP was found at ca. -10 ppm. Furthermore, P-C bond stretching vibration peaks were found ca. $530cm^{-1}$ in FT-IR spectrums of PET-RDP. These results indicated that RDP can be chemically bound at the ends of PET by radical addition method. Thermal characteristics of pure PET (pPET) and PET-RDP were measured and evaluated by TGA thermal analysis. There was not significant changes in thermal characteristics of PET-RDP compared to that of pPET.

• 한국태양에너지학회 논문집
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• 제34권6호
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• pp.11-18
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• 2014

Two-step water splitting thermochemical cycle with $CeO_2$ foam device was investigated by using a solar simulator composed of 2.5 kW Xe-Arc lamp and mirror reflector. The hydrogen production of $CeO_2$ foam device depending on reaction temperature of Thermal-Reduction step and Water-Decomposition step was analyzed, and the hydrogen production of $CeO_2$ and $NiFe_2O_4/ZrO_2$ foam devices was compared. As a result, the amount of reduced $CeO_2$ considerably varies according to the reaction temperature of Thermal-Reduction step. and hydrogen production was not much when the amount of reduced $CeO_2$ decreased even if the reaction temperature of Water-Decomposition step was high. Therefore, it is very important to keep the reaction temperature of Thermal-Reduction step high in two-step thermochemical cycle with $CeO_2$.

• Nuclear Engineering and Technology
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• 제51권3호
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• pp.746-754
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• 2019

Vitrification of radioactive liquid waste (RLW) provides a feasible solution for isolating radionuclides from the biosphere for an extended period. In vitrification, base glass and radioactive waste are added simultaneously into the melter. Determination of heat and mass transfer rates is necessary for rational design and sizing of melter. For obtaining an assured product quality, knowledge of reaction kinetics associated with the thermal decomposition of waste constituents is essential. In this study Thermogravimetry (TG) - Differential Thermogravimetry (DTG) of eight kinds of nitrates and two oxides, which are major components of RLW, is investigated in the temperature range of 298-1273 K in the presence of base glasses of five component (5C) and seven component (7C). Studies on thermal behavior of constituents in RLW were carried out at heating rates ranging from 10 to $40\;K\;min^{-1}$ using TG - DTG. Thermal behavior and related kinetic parameters of waste constituents, in the presence of 5C and 7C base glass compositions were also investigated. The activation energy, pre-exponential factor and order of the reaction for the thermal decomposition of 24% waste oxide loaded glasses were estimated using Kissinger method.

• 대한화학회지
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• 제19권5호
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• pp.367-374
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• 1975

N-X-glycylphenylalanine methyl ester(X-trifluoroacetyl or acetyl)의 글리신잔기를 광 알킬화 반응에 의해 aspartic acid 의 유도체로 전환하였다. 이 반응은 diacetyl/di-t-butyl peroxide(DBP)를 광 개시제로, acetic anhydride를 알킬화제로 하여 350nm 파장의 램프를 사용하므로써 일어난다. DBP와 acetic anhydride에 의한 열반응의 경우에도 같은 알킬화 반응을 관찰하였다. 이 열알킬화 반응은 자유라디칼 반응을 거쳐 일어나기 때문에 이와 비교하여 광 알킬화 반응도 자유라디칼 메카니즘에 의해 일어난 것으로 추측된다.

• Bulletin of the Korean Chemical Society
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• 제23권2호
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• pp.325-329
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• 2002

In this study, the dependency of the behavior of propagating front on the reaction condition in frontal polymerization reaction has been studied. We have used some multifunctional acrylates as a monomer and ammonium persulfate as an initiator for the polymerization reactions. In frontal polymerization, a method of producing polymeric materials via a thermal front that propagates through the unreacted monomer/initiator solution, the behavior of self propagating front shows various dynamic patterns depending on the reaction condition. We have obtained some spin modes of propagating front in the number of 'hot spots' or 'spin heads' by changing the reaction condition. The effect of the reactor tube diameter on the mode of propagating front has also been studied by using some reactor tubes with different size of tube diameter and it has been examined in some detail by adopting an experimental method of two-tubes system.

• 한국식품영양학회지
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• 제11권3호
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• pp.267-271
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• 1998

Seyferth 시약인 phenyl(tribromomethyl) mercury 및 diazomethane의 식품보존제인 dehydroacetic acid 및 coumarin과의 발암성과 그 반응기작을 분자 구조적 관점에서 알아보기 위하여 UV/vis 조건과 laser flash photolysis 시켰을 때의 결과는 다음과 같다. 1. Diazomethane과 Phenyl(tribromomethyl) mercury와 dehydroacetic acid와 diazomethane과의 반응은 광화학적 분해 반응에서 생성된 : CBr2와 : CH2 카르벤 중간체의 이탈기 효과에 따라 발암성이 크게 나타났다. 2. laser flash photolysis 상에서 반응시켰을 때 식품보존제의 발암성이 UV/vis 상에서의 photolysis 때보다 크게 나타났다.

• 한국잠사곤충학회지
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• 제40권2호
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• pp.131-135
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• 1998

Changes of silk fibroin molecular weight was studied by enzymatic proteolysis and reverse reaction of enzymatic proteolysis (plastein reaction) using chromatography, X-ray diffraction and thermal analysis methods. When the treatment of enzymatic proteolysis with $\alpha$-chymotripsin to silk fibroin solution, a precipitate of Fcp fractions was formed. And, this was dissolved in LiBr aqueous solution, the precipitate of PIFcp fractions was obtained again. Fcp and PIFcp fractions showed silk IIand silk Itype structure, respectively. Fcp fractions was about 6,900 in molecular weight, PIFcp fractions obtained by plastein reaction on the precipitate of Fcp fractions increased molecular weight to abort 15,000. The molecular weight of Fcp fractions was increased by plastein reaction, but Fcp fractions almost transited to silk I type crystal. The structure of silk I type of PIFcp fractions was steady identified by X-ray diffraction and thermal analysis. As molecular weight of Fcp fractions was gradually low, PIFcp fractions was become to macromolecule little by little.

• 대한약침학회지
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• 제4권1호
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• pp.103-104
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• 2001

This study was done to observe the effect on the local thermal changes of herbal acupuncture on D.I.T.I.. The objects of this study are as follows; If there are remarkable local thermal changes between pre and post herbal acupuncture therapy on D.I.T.I.or not. If there are those, We examine how long that changes are maintained, what the adequate interval is on herbal acupuncture therapy, and what the reaction in a .local or whole body are on that therapy Materials and Methods : To study the local thermal changes in herbal acupuncture therapy, D.I.T.I. was used. Determination of this analysis periods are pre and post-therapy(1 hour, 24hours, 48hours and 7days later). The study group was divided into three groups(comprised 23 students in oriental medical college, Woosuk University). One was NS(Normal Saline) group, another was CF(CARTHAMI SEMEN) group and the other was BU(FEL URSI + BENZOAR BOVIS) group. The Herbal Acupunture solution was injected 0.2ml divide into 0.05ml at tile P'ungmun(B12), P'yesu(B13), Pubun(B41), Paek'o(B42) 4 points. Then, in order to analyze the clinical form, we have observed response of 23 students whenever we checked the thermal changes of their after perfoming Results : The results were obtained as follows ; 1. There is no significant dermatothermal changes at NS group and CF group, but BU group have remarkable changes in 24, 48, 72 hours. 2. From post-therapy 1 hour to 48 hours, there is a significant change (P<0.01) at NS-BU group and CF-BU group, But there is none 7 days later. 3. In the analysis of whole or local body reaction, local pain appears at NS group(22%), CF group(11%), BU group(91%), discomfort reaction appears at CF group(14%), BU group(30%). BU groilp has feel vertigo(13%), drowsy (70%) and pain in action(52%). 4. In the analysis of the duration of physic진 reaction, BU group is most lately maintained. Conclusions : These results suggest that in the physical reaction of herbal acupuncture solutions, BU solution is more sensitive than CF solution or NS.

• 한국태양에너지학회 논문집
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• 제33권3호
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• pp.42-50
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• 2013

Solar thermal reactor was studied for hydrogen production with a two step thermochemical cycle including T-R(Thermal Reduction) step and W-D(Water Decomposition) step. NiFe2O4 and Fe3O4 supported by monoclinic ZrO2 were used as a catalyst device and Ni powder was used for decreasing the T-R step reaction temperature. Maintaining a temperature level of about $1100^{\circ}C$ and $1400^{\circ}C$, for 2-step thermochemical reaction, is important for obtaining maximum performance of hydrogen production. The controller was designed for adjusting high temperature solar thermal energy heating the foam-device coated with nickel- ferrite powder. A Pill temperature control system was designed based on 2-step thermochemical reaction experiment data(measured concentrated solar radiation and the temperature of foam device during experiment). The cycle repeated 5 times, ferrite conversion rate are 4.49~29.97% and hydrogen production rate is 0.19~1.54mmol/g-ferrite. A temperature controller was designed for increasing the number of reaction cycles related with the amount of produced hydrogen.