• 대한원격탐사학회지
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• 제37권6_1호
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• pp.1491-1506
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• 2021

GEMS의 복사 실측 자료로부터 일산화브로민(BrO) 전량 농도를 산출하기에 앞서, 복사전달모델로부터 생성된 모의자료를 이용하여 민감도 시험을 수행하였다. 산출 오차가 갖는 월간 및 일내 변동성을 고려하기 위해, 2013년 7월-2014년 6월 기간 매달 첫째 날의 00-07 UTC에 대해 한 시간 간격의 모의자료를 구성하였다. 최적추정법을 통해 계산된 산출물의 해답 오차는 대기질량인자 증가에 따라 감소하는 반비례 경향을 주로 보였지만, 대기질량인자 값이 5 이상으로 크게 나타나는 범위에서는 비례 경향을 보였다. BrO와 포름알데히드(HCHO) 흡수선 간의 중첩으로 인해 발생하는 BrO 산출물의 간섭 오차는 BrO의 대기질량인자가 작을수록 크게 나타났다. 해답 오차와 간섭 오차의 추정치를 결합하여 계산한 산출물 최종 오차의 평균값은 모든 데이터 샘플에 대해 26.74±30.18%로, 80° 이상의 태양천정각을 갖는 샘플에 대해 60.39±133.78%로 나타났다. 본 연구에서 고려되지 않은 간섭 스펙트럼 및 복사 측정의 오차로 인해, 실제 GEMS의 BrO 산출물이 갖게 될 오차는 추정치와 절대값의 차이를 나타낼 가능성이 있다. 그러나 본 연구에서 제시한 오차 요소들의 변동 특성들은 실제 산출물에서도 나타날 것이다.

• 한국응용과학기술학회지
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• 제23권3호
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• pp.264-271
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• 2006

PU type flame-retardant coatings (TBAO/L-75, TBAOL ; TBAO/N-100, TBAON) were prepared by blending bromine-containing modified polyester (TBAO) which was synthesized in our earlier work. with two kinds of isocyanate curing agents, Desmodur L-75 and Desmodur N-100. Physical properties of the prepared flame-retardant coatings were tested. TBAOL shows better hardness than TBAON, while TBAON shows better viscosity, accelerated weathering resistance, yellowness index and lightness index difference than TBAOL. There were no remarkable differences in fineness of grind, $60^{\circ}$ specular gloss, cross-hatch adhesion, and abrasion resistance of TBAOL and TBAON. There was no discernable difference in flame-retardancy between the two flame-retardant coatings, TBAOL and TBAON. When the content of tribromo acetic acid, which is flame-retarding component, was 30wt% the LOI value was in a range of $29{\sim}30%$, which indicates that the two coatings are good flame-retardant coatings.

• 한국수정란이식학회지
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• 제26권4호
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• pp.297-304
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• 2011

Polybrominated diphenyl ethers (PBDEs) are a class of "brominated" (bromine containing) man-made chemicals used as flame retardant additives in plastics, foams, and textiles. PBDEs are found in various environmental contaminants in air, soil, sediment, and water, and 209 individual forms (congeners) of PBDE exist. Among these, 2,2',4,4'-tetrabromodiphenyl ether (BDE-47) is the dominant congener found in the environment. Exposure to BDE-47 is now worldwide, and levels of BDE-47 have been detected in the blood of animals, including humans. BDE-47 can adversely affect the developmental system in both humans and animals. BDEs have structural similarities to polychlorinated biphenyls and thyroid hormones. However, recent studies have shown that BDEs may act as hormonal disrupting chemicals with detrimental effects. Therefore, a reliable assessment of BDE-47 toxicological action is required to understand the detrimental impacts of BDE-47 on human health. In this review, we overview recent studies on the distribution and potential toxicological effects of BDE-47 in humans and animals.

• 한국환경과학회지
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• 제13권7호
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• pp.667-674
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• 2004

The objective of this study was to investigate the effects of pH and temperature on the formation of bromate, which is ozonation by-products, during ozonation. In this experiment, the operating parameters including pH 3 ～ 10 and temperature 15 ～ $30^{\circ}C$ were studied. Through the study for the bromate formation, reaction rate constant, and ozonation effect index on pH and temperature, the results obtained are as follows. At the same initial pH condition, the increase of pH shown similar trends even if the reaction variables such as temperature and reaction time of ozonation were exchanged. As pH and temperature were increasing, the bromate concentration was increased but bromine(HOBr+OBr) was decreased with increasing pH from 3 to 10. The activation energy(J/mol) for bromate formation decreased with increasing pH. The rate constants of bromate formation for the reaction of ozone and bromide, and ozone dosage coefficient$(K_{0})$ increased with temperature and pH. Ozonation effect index(OI) decreased with increasing temperature and pH.

• Macromolecular Research
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• 제15권6호
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• pp.541-546
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• 2007

The combination of atom transfer radical polymerization (ATRP) and click chemistry was employed for the efficient preparation of well-defined block copolymers. Bromo terminated poly(methyl acrylate) (pMA-Br) was prepared by an ATRP initiator, ethyl-2-bromoisobutyrate (EBiB). Subsequently, the bromine chain end of pMA-Br was converted to an azide group by simple nucleophilic substitution reaction. ${\alpha}-Alkyn-{\omega}-bromo-functionalized$ polystyrene was also synthesized by ATRP using the alkyn-functionalized initiator, propargyl-2-bromoisobutyrate (PgBiB). In both cases, the conversion was limited to a low level to ensure a high degree of chain end functionality. Then the coupling reaction between the azide end group in $pMA-N_3$ and alkyn-functionalized PgBiB-pSt was performed by Cu(I)catalysis. This coupling reaction was monitored by gel permeation chromatography (GPC). The synthesized block copolymer was characterized by FT-IR, $^1H-NMR$ spectroscopy and $^1H-^1H$ COSY correlation spectroscopy.

• Bulletin of the Korean Chemical Society
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• 제29권1호
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• pp.51-56
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• 2008

The regioselective ring opening of epoxides using elemental iodine and bromine in the presence of methimazole (MMI, a anti-thyroid drug) and its metabolite methimazole-disulfide as new catalysts are studied. MMI easily converted in vitro to MMI-disulfide without any double activation presented in vivo. FT-Raman and UV spectroscopies are used to study the interaction of iodine with these catalysts. The results indicate that both catalysts are efficient in polyiodide formation, but MMI-disulfide can catalyze this reaction in higher yield and regioselectivity. The complex [(MMI-disulfide)I]+.I3- is considered to be formed initially which could be bulkier by addition of excess of iodine in the course of the reaction. These bulky nucleophiles have a fundamental role in the high regioselectivity by attacking the less sterically hindered epoxide carbon. In this study we suggest that MMI is readily converted to MMI-disulfide by interaction with iodine or activated iodine in thyroid gland, and this process is responsible for high anti-thyroid activity of MMI.

• 한국대기환경학회지
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• 제11권3호
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• pp.279-290
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• 1995

Recently in Korea, due to the significant drop of lead and bromine levels as a marker of autoemission source in the urban areas, the conventional application of receptor methods has many difficulties to properly apportion mass contribution of some sources. It is then needed to urgently develop alternative source profiles and identify new emission markers. Thus, the study has extensively examined the results obtained from using PAHs and elemental data for receptor modeling and has provided an opportunity to identify alternative source compositions and to determine a proper number of the ambient emission sources in Seoul area. The purpose of the study is to identify the sources of PM-10 and to estimate their mass contributions in Seoul area. Thus, a receptor model, target transformation factor analysis(TTFA) has been massively applied. The TTFA offers the possibility of determining the number of sources and their mass contributions. The input data used in this study are composed of two separate sets: fine (d$_{p}$ < 2.5.mu.m) and coarse (2.5.mu.m < d$_{p}$ < 10.mu.m) mode aerosol samples. Each sample was simultaneously collected by a PM-10 dichotomous sampler during the daytime(8 AM to 8 PM) and the nighttime(8 PM to 8 AM) from February to October 1993 on the Sungdong-Gu, Seoul. All the samples were analyzed to determine the levels of 10 inorganic elements by an XRF system as well as 14 PAHs by a HPLC. However, only 8 inorganic elements and 7 PAHs were used for the various statistical analysis.sis.

• 대한화학회지
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• 제19권6호
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• pp.403-407
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• 1975

히드라진과 브롬의 반응속도를 직접 혼합법 및 일정전류 전해법에 의한 브롬화 이온의 전이시간을 측정하는 방법으로 측정하여, 황산 및 브롬화칼륨의 농도가 작을 때에 2차 반응속도 상수는 각각 $10^5\;및\;10^3mole^{-1}sec^{-1}$로 얻어졌다. 이는 $N_2H_4+Br_2{\rightarrow}N_2H_2,k_1=10^5$ 및 $N_2H_2+Br_2{\rightarrow}X,k_2=10^3$인 것으로 간주된다. 황산과 브롬화 이온의 농도가 클때에는 속도상수가 크게 감소하나 그 원인은 해명하지 못하였다.

• Mass Spectrometry Letters
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• 제2권1호
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• pp.24-27
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• 2011

Hyperthermal ion/surface collisions of bromotoluene radical cations were studied using perfluorinated (F-SAM) and hydroxyl-terminated (OH-SAM) self-assembled monolayer surfaces in a tandem mass spectrometer with BEEQ geometry. The isomers were differentiated by ion abundance ratios taken from surface-induced dissociation (SID). The dissociation rate followed the order of ortho > meta > para isomers. The peak abundance ratio of m/z 51 to m/z 65 showed the best result to discern the isomers. A dissociation channel leading to tolylium ion was suggested to be responsible for the pronounced isomeric differences. The capability of SID to provide high-energy activation with narrow internal energy distribution may have channeled the reaction into the specific dissociation pathway, also facilitating small differences in reaction rates to be effective in the spectral time window of this experiment. All of the molecular ions experiencing reactive collisions with the F-SAM surface undergo transhalogenation, in which a fluorine atom on the surface replaces the bromine in the incoming ions. This reactive collision was dependent on the laboratory collision energy occurring in ca. 40.75 eV range.

• Bulletin of the Korean Chemical Society
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• 제24권9호
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• pp.1276-1280
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• 2003

Thermal behavior of bromphenols was investigated by direct pyrolysis at high temperature. The thermal degradation products formed by the pyrolysis of mono-bromophenols (o-, m-, and p-) were identified by gas chromatography-mass spectrometry. During the pyrolysis reactions, several kinds of dioxins and furans were produced, and the relative ratio of pyro-products was dependent on the substituted position of bromine in phenolic structure due to the effect of symmetry and steric hindrance. The formation of dioxins can be explained by the phenoxy radical addition and Br atom elimination at an ortho-carbon site on phenolic structure. On the other hand, the formation of furans can be explained by the ortho-ortho carbon coupling of phenoxy radicals at unsubstituted sites to form o, o'-dihydroxydiphenyl intermediate via its keto-tautomer, followed by $H_2O$ elimination. The pyrolysis temperature has also a substantial effect on the dimerized products quantities but little effect on the type of pyro-products. Moreover, the formation mechanism of pyro-products was suggested on the basis of products identified.