• Bulletin of the Korean Chemical Society
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• 제3권3호
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• pp.110-115
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• 1982

Thermochemistry and photochemistry of picolyl chlorides were studied. The thermal reaction of 2-picolyl chloride in benzene afforded intermolecular condensation product. In the case of 3-picolyl chloride, this type of the reaction did not occur, but polymers were obtained. A cyclic hexamer, suggested by a molecular model, was not formed because of the steric strain and low reactivity. The thermal reaction of 4-picolyl chloride gave a cyclic hexamer as well as a polymer. The cyclic hexamer, identified by NMR spectrum, showed ${\lambda}_{max}$ at 460 nm. The cyclic hexamer was cloven to the linear structure. Photolysis of 2-picolyl chloride at 253.7 nm gave a para-isomer followed by polymerization. When a methyl hydrogen of 2-methylpyridine is substituted by $CH_3O$, iso-PrO, and EtO group, the photoisomerization to the corresponding anilines or para-substituted pyridines did not occur within the range of the time used for 2-picolyl chloride. Thermolysis of picolyl chlorides in an acidic methanol solution did not afford any product.

• Bulletin of the Korean Chemical Society
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• 제22권9호
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• pp.999-1004
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• 2001

(1-Chloro-2,2-dicyanovinyl)benzene or 1,4-bis(1-chloro-2,2-dicyanovinyl)benzene was reacted with 2-amino-phenol to give the model compound, hydroxy enaminonitrile, which was found to undergo thermal cyclization reaction to form the corresponding benzoxazole. This intramolecular cyclization reaction is expected to occur through nucleophilic attack to electropositive enamine carbon by ortho-hydroxy group on the phenyl ring, which is accompanied by the release of neutral malononitrile through rearrangement. From each bifunctional monomer, o-hydroxy substituted polyenaminonitrile was prepared and characterized as a new precursor polymer for well-known aromatic polybenzoxazole. Also the unusual macrocyclic dimer formation from the 1,4-bis(1-chloro-2,2-dicyanovinyl)benzene and 2,2-bis(3-amino-4-hydroxyphenyl)hexafluoropropane polymerization reaction system was discussed. The thermal cyclization reactions and the properties of polymers were investigated using FT-IR and thermal analysis (DSC & TGA).

• Nuclear Engineering and Technology
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• 제49권5호
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• pp.1019-1030
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• 2017

Diffusion is a crucial mechanism that regulates the migration of radioactive nuclides. In this study, an innovative numerical method was developed to simultaneously calculate the diffusion coefficient of both parent and, afterward, series daughter nuclides in a sequentially reactive through-diffusion model. Two constructed scenarios, a serial reaction (RN_1 ${\rightarrow}$ RN_2 ${\rightarrow}$ RN_3) and a parallel reaction (RN_1 ${\rightarrow}$ RN_2A + RN_2B), were proposed and calculated for verification. First, the accuracy of the proposed three-member reaction equations was validated using several default numerical experiments. Second, by applying the validated numerical experimental concentration variation data, the as-determined diffusion coefficient of the product nuclide was observed to be identical to the default data. The results demonstrate the validity of the proposed method. The significance of the proposed numerical method will be particularly powerful in determining the diffusion coefficients of systems with extremely thin specimens, long periods of diffusion time, and parent nuclides with fast decay constants.

• Bulletin of the Korean Chemical Society
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• 제8권4호
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• pp.298-300
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• 1987

The theoretical studies on the photocycloaddition reaction of 5,7-dimethoxycoumarin and 4',5'-dihydropsoralen with thymidine were carried out as a model for photosensitizing reaction of psoralen with DNA. The results are in reasonable agreement with experimental observations. The photoadducts between dimethoxycoumarin and thymidine were predicted to be $C_{4}$-cycloadducts through the cycloaddition of 3,4-pyrone double bond of dimethoxycoumarin to 5,6 double bond of thymidine. The major photoadduct of 4',5'-dihydropsoralen with thymidine has the anti head-to-head stereochemistry.

• Korean Chemical Engineering Research
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• 제52권1호
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• pp.133-140
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• 2014

본 연구의 목적은 국내 화력발전소에서 사용중인 인도네시아 석탄촤의 연소반응율을 연구하는 것이다. 석탄촤의 반응율은 External, Internal effectiveness factor를 고려하여 입자 내부 및 외부확산을 정량적으로 정리하였으며, Random pore model을 사용하여 탄소변환율에 따른 입자내부비표면적의 변화를 반영하였다. 가열 및 측정이 가능한 WHR(Wire Heating Reactor)를 활용하여 반응시간을 측정함으로써 석탄촤의 반응율을 도출하였고 BET(Brunauer-Emmett-Teller) 및 TGA(Thermo-Gravimetric Analysis) 장비를 활용하여 석탄촤의 물리적인 특성인 내부비표면적과 Random pore model의 구조변수(${\Psi}$)를 측정하였다. 석탄 종에 따른 활성화에너지 및 빈도인자를 도출하기 위해 아역청탄인 BARAMULTI, ENERGYMAN, AGM탄을 사용하였다. 본 연구 결과에서 External, Internal effectiveness factors를 통해 확산에 따른 kinetics를 비교한 결과 외부 확산 보다 내부 확산의 영향이 지배적임을 확인하였다. 최종적으로 내부 및 외부 확산에 대한 영향을 고려한 3종의 석탄촤 Intrinsic kinetics의 활성화에너지는 110~118 kJ/mol의 값을 보였다.

• 청정기술
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• 제20권1호
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• pp.64-71
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• 2014

열중량분석기를 이용하여 이산화탄소 분위기에서 알칼리계 염류가 에코(Eco)탄의 가스화 반응에 미치는 영향을 알아보았다. $750{\sim}900^{\circ}C$에서 탄산칼륨, 탄산나트륨, 탄산칼슘, 백운석(Dolomite) 7 wt%의 알칼리염을 첨가한 것과 원탄을 이용하여 실험을 진행하였다. $850^{\circ}C$에서의 가스화 결과, 이산화탄소의 농도가 증가할수록 반응속도가 증가하는 경향을 관찰하였다. 그러나 70% 이상의 농도에서는 반응속도의 증가량이 크게 증가하지 않음을 관찰하였다. 가스화 반응속도는 7 wt% 탄산나트륨 > 7 wt% 탄산칼륨 > 원탄> 7 wt% 백운석 > 7 wt% 탄산칼슘 순으로 나타났다. $700^{\circ}C$, $800^{\circ}C$, $850^{\circ}C$ 그리고 $900^{\circ}C$의 등온, 상압조건에서 가스화 실험 결과, 온도가 증가할수록 반응속도가 증가함을 관찰하였다. 차(char)-이산화탄소 가스화 반응의 기-고체 모델은 volumetric reaction model (VRM)이 탄소 전환율 거동을 가장 잘 묘사했다. 이를 이용하여 얻은 탄산나트륨의 활성화 에너지는 83 kJ/mol로 가장 낮게 얻어졌다.

• 대한안전경영과학회지
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• 제15권3호
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• pp.151-161
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• 2013

This paper proposes a strategic model of linkage between productivity metrics and financial accounting metrics to properly evaluate the financial effect of TPM activities and the business performance. This linkage strategy provides a connection tool for clear communication between factory-level and headquarters that the metrics proposed by this paper ultimately improves a quality of support from the management by receiving the factors required for productivity activities in the practical field. This factor includes such as equipment, raw materials and labors. Here, we propose that chain reaction models using break down structure of productivity metrics and financial metrics enhance the knowledge sharing of KPI (Key Performance Indicator) which generally tend to create oversimplified communication between management in headquarters and employees in the practical fields. The productivity metrics include OEE(Overall Equipment Effectiveness) of TPM (Total Productive Maintenance), OLE (Overall Labor Effectiveness) of PAC(Performance and Analysis and Control) activities, and OYE (Overall Yield Effectiveness) of TMM(Total Material Management) activities. The financial accounting metrics include ROE(Return on Equity), ROA(Return on Asset), and AVR(Added-Value Rate). The suggested chain reaction model selects the financial metrics as initial stage and branch down until final stage of productivity metrics. When demand exceeds supply, an ideal speed rate, the lean OEE strategy can be initially applied to reduce the gap between the demand and supply, then apply variable costing to estimate correct amount of operating profit. In addition, the paper presents a new type of model for linkage between financial accounting metrics including CAPEX(Capital Expenditure), OPEX(Operating Expenditure), EVA(Economic Added Value), DCL(Degree of Combined Leverage), and TPM productivity activities including AM(Autonomous Maintenance), PM(Preventive Maintenance), MP(Maintenance Prevention) and QM(Quality Maintenance). In order to support the evidence of proposed linkage strategy, a case analysis on 52 projects from national TPM contest from 2011 to 2012 is analyzed. The case presents the classification of CAPEX and OPEX activities from TPM, and proposes the correct implementation of financial effect for TPM projects.

• 한국지능시스템학회논문지
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• 제26권2호
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• pp.127-134
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• 2016

본 논문에서는 원판의 반작용을 이용하는 역진자의 강인 자세 제어를 위한 강인 제어 기법을 소개한다. 이를 위해 원판 반작용을 이용하여 자세 조정이 가능한 시스템을 설계한다. 설계된 시스템의 수학적 모델을 구하고 그 수학적 모델을 이용하여 제어기를 설계한다. 설계한 강인 제어 기법은 두 부분으로 구성되어 있다. 초기에는 역진자의 swing up을 위한 수동성 기반의 제어기(passivity based control)를 사용하고 역진자의 자세가 수직 위치 근방에 오면 강인 안정화 제어기로 제어기를 변경한다. 강인 안정화 제어기가 필요한 이유는 역진자 시스템에서 관성 모멘트를 불확실성을 다루기 위함이다. 모의 실험과 실제 실험을 통해 제안하는 제어기가 효과적으로 원판 반작용에 기반한 역진자의 자세 제어를 달성함을 보인다.

• KEPCO Journal on Electric Power and Energy
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• 제3권1호
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• pp.29-34
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• 2017

Leaching kinetics for extracting yttrium from the coal fly ash was investigated in the presence of sulfuric acid during extraction. The leaching kinetics of yttrium were conducted at reactant densities of 5~1,000 g coal fly ash per L of $1.0{\sim}10.0N\;H_2SO_4$, agitation speed of 250 rpm and temperature ranging from 30 to $90^{\circ}C$. As a result, the leaching kinetic model was determined in a two-step model based on the shrinking core model with spherical particles. The first step was proceeded by chemical reaction at ash surface, and the second step was proceeded by ash layer diffusion because the leaching conversion of yttrium by the first chemical reaction increases with increased the time irrelevant to the temperature whereas it increases with increased the leaching temperature. The activation energy of the first chemical leaching step was determined to be $1.163kJmol^{-1}$. After the first chemical reaction, the activation energy of ash layer diffusion leaching was derived to be $41.540kJmol^{-1}$. The optimum conditions for leaching the yttrium metal of 60 % were found to be the slurry density of 250 g fly ash per L of $H_2SO_4$, solvent concentration of $2.0N\;H_2SO_4$, second step leaching of temperatures of $30^{\circ}C$ for 3 hours and then $90^{\circ}C$ for 3 hours at agitation rate of 250 rpm.

• 공업화학
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• 제5권3호
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• pp.385-394
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• 1994

세공분포가 서로 다른 두 종류(KHT, X-5)의 ${\gamma}$-알루미나 pellet에 아황산가스를 흡착 제거시킬 경우 반응이 진행되면서 각각의 세공벽에 반응생성층이 형성되어 반응속도 상수($K_v$), 세공률(${\varepsilon}_p$), 유효내부 확산계수($D_e$)의 변화와 세공반경이 줄어들어 세공막힘 현상이 일어나게 된다. 이들 영향을 고려하여 세공분포를 이용한 Random pore model로 최적반응온도 $450^{\circ}C$에서 산화구리의 각 담지농도(4, 6, 8, l0 wt%)와 아황산가스의 농도(1000, 2000ppm)에 대한 전환율을 수학적 모델로부터 계산하였다. 산화구리의 담지농도가 증가할수록 세공내의 유효반응 표면적과 세공률의 감소, 내부확산저항의 증가, 미세세공의 세공막힘 현상으로 전환율은 감소하였다. 총괄 전환율은 ${\gamma}$-알루미나 pallet의 표면 국부 전환율에 크게 의존하였으며 산화구리의 담지농도가 낮고 아황산가스의 농도가 클수록 증가하였다. 반응기에 유입되는 아황산가스의 유속은 반응초기 CuO의 전환율에 영향을 주었고 세공분포가 발달하여 세공율이 큰 ${\gamma}$-알루미나 pellet일수록 전환율은 높게 나타났다.