• Journal of the Korea Furniture Society
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• v.19 no.2
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• pp.116-123
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• 2008

Kiln schedule development was based on two schedule phases, the first being to determine the maximum safe kiln temperature during the check prone initial stage of drying, with the second stage determining how to accelerate drying once the danger of checking had passed. This was achieved by using 38 mm thick boards which were pre-screened for susceptibility to internal checking, and then drying matched sample boards over a range of kiln temperatures. Research has shown that below 50% MC there is no further risk of internal checking. However, difference in drying rate due to board width and the increased occurrence of wet patches in wide boards means that it is essential to modify the basic schedule according to the maximum board width. A condition of 52/40 $^{\circ}C$ was selected for the checking-free initial kiln drying step and a 5-step kiln-schedule dried the boards from 109% to 8% MC for 72.5 hours without internal checking.

• FOCUS: LIFE SCIENCE
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• no.1
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• pp.9.1-9.5
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• 2024

Method development for complex low molecular mass (LMM) samples using reversed-phase (RP) separation conditions presents significant challenges due to the presence of many unknown analytes over wide concentration ranges. This guide aims to optimize method parameters-column length (L), temperature (T), flow rate (F), and final mobile phase conditions (Øfinal)-to maximize separation peak capacity. Validated by prior research, this protocol benefits laboratories dealing with metabolomics, natural products, and contaminant screening. This practical guide provides a structured approach to maximizing peak capacity for complex LMM separations. It complements computational optimization strategies and offers a step-by-step method development process. The Snyder-Dolan test is highlighted as essential for determining the need for gradient or isocratic elution and guiding column length decisions. The decision tree framework helps analysts prioritize variable optimization to develop effective separation methods for complex samples.

• Bulletin of the Korean Chemical Society
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• v.34 no.12
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• pp.3795-3799
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• 2013

The second-order rate constants ($k_N$) have been measured spectrophotometrically for nucleophilic substitution reactions of Y-substituted-phenyl 2-methylbenzoates (6a-e) with a series of cyclic secondary amines in MeCN at $25.0{\pm}0.1^{\circ}C$. Comparison of the $k_N$ values for the reactions of 4-nitrophenyl 2-methylbenzoate (6d) with those reported previously for the corresponding reactions of 4-nitrophenyl 2-methoxybenzoate (5) reveals that 6d is significantly less reactive than 5, indicating that modification of 2-MeO in the benzoyl moiety of 5 by 2-Me (i.e., $5{\rightarrow}6d$) causes a significant decrease in reactivity. This supports our previous report that aminolysis of 5 proceeds through a six-membered cyclic intermediate, which is highly stabilized through intramolecular H-bonding interactions. The Br${\o}$nsted-type plot for the reactions of 6d with a series of cyclic secondary amines is linear with ${\beta}_{nuc}=0.71$, which appears to be a lower limit of ${\beta}_{nuc}$ for a stepwise mechanism with breakdown of an intermediate ($T^{\pm}$) being rate-determining step (RDS). The Br${\o}$nsted-type plot for the reactions of 6a-e with piperidine is curved, i.e., the slope of Br${\o}$nsted-type plot (${\beta}_{lg}$) decreases from -1.05 to -0.41 as the leaving-group basicity decreases. The nonlinear Br${\o}$nsted-type plot has been taken as evidence for a stepwise mechanism with a change in RDS (e.g., from the $k_2$ step to the $k_1$ process as the leaving-group basicity decreases). Dissection of $k_N$ into the microscopic rate constants associated with the reactions of 6a-e with piperidine (e.g., $k_1$ and $k_2/k_{-1}$ ratio) also supports the proposed mechanism.

• Journal of the Korean Chemical Society
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• v.37 no.2
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• pp.199-205
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• 1993

The decomposition of hydrogen peroxide by copper-amines complexes was studied in the pH range of 7.3∼11.3 by measuring the rate of the decreasing concentration of $H_2O_2$. Decomposition rate of hydrogen peroxide increased with increasing pH, and then decreased with increasing pH successively. The mechanism for this type of reaction involves the formation of peroxo complexes in the rate-determining step preceding deprotonation of hydrogen peroxide and copper-amines complexes.

• Journal of the Korean Chemical Society
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• v.31 no.3
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• pp.280-286
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• 1987

The effect of substituent inleaving group on the rates of reactions of phenacyl substituted-benzenesulfonates with pyridine was determined conductometrically in acetonitrile and in methanol at 35, 45, and $55^{\circ}C$, respectively. The reaction rate became faster in proportion to electron-attracting ability of substituent, which indicates that the substituent in leaving group can directly control reaction rate. It was shown that the specific to the carbonyl carbon as the rate-determining step.

• Journal of the Korean Chemical Society
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• v.16 no.1
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• pp.1-5
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• 1972

The adsorption kinetics on a membrane filter have been studied by an introduction of acid or alkali in yttrium-90 solution. The change of the adsorption in the filtration process was determined by the filtrate activities with using a microsyringe filter holder connected with a syringe. The over all reaction rate obeyed a reversible first order reaction, and the rate constants thus obtained, showed the values of $k_1$ = 0.12 $sec^{-1}$ and $k_1'$ = 0.039 $sec^{-1}$. As a result of the present studies, it would be reasonable that the rate determining step of the adsorption reaction was the hydrolysis reaction of the adsorbed yttrium ions.

• Magazine of the Korean Society of Agricultural Engineers
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• v.33 no.3
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• pp.91-100
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• 1991

Since ventilation in livestock buildings is critical for indoor air quality, the first step in designing environmental control is to determine required ventilation rate. The purpose of the study was to suggest a conceptually new ventilation graph for determining minimum/maximum ventilation rate based on the conservation law of the thermal energy and mass in livestock buildings. PC-based programs coded with PASCAL language, [RVALUE] for overall thermal resistance of composite structural walls/ceilings, [POLYNOM] for coefficients values of animal's sensible heat equation were involved in developing a computer program, [VENTGRPH] for the determination of ventilation rate. It would be useful for design, for such a program would permit the designer to explore various design options and immediately, see the result in terms of its effect on minimum ventilation rates.

• Journal of the Korean Ceramic Society
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• v.26 no.4
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• pp.514-520
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• 1989

The early hydration characteristics according to the C3S/C3A ratio and presence of gypsum, in order to establish the hydration mechanism of the system C3S-C3A, have been studied. The rate of C3S dissolution in the system C3S-Gypsum was higher than that in the system C3S. Consequently, the induction period was reduced and the rate of Ca(OH)2 formation in the accleration period was increased. The hydration of C3S in the system C3S-C3A was retarded because Al3+ in the liquid phase originating from the hydration of C3A was incorporated into calcium hydrosilicates formed. The retardation phenomenon of C3S hydration was not appeared in the system C3S-C3A-gypsum because the reaction of monosulfate formation became the rate-determining step.

• Journal of the Korean Chemical Society
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• v.16 no.2
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• pp.84-92
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• 1972

A mechanism for the ring formation of nickel phthalocyanine (Ni-Pc) has been proposed based on chemical kinetics. The effect of the catalyst on the rate was examined, and ammonium molybdate has been found to be the most effective. The reaction order of the ring formation was determined to be of the 1st order over all, with only the concentration of urea affecting the rate of the ring formation. All the results including thermodynamic parameters support a conclusion that the rate-determining step seems to be the enolization of the urea-catalyst transition complex, followed by fast decomposition of the tautomeric enolized urea into ammonia and isocyanic acid. These intermediates then reacted with the phthalic anhydride to form imino and diimino-phthalimide, which condense to form nickel phthalocyanine in the presence of the nickel cation.

• Bulletin of the Korean Chemical Society
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• v.27 no.2
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• pp.255-265
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• 2006

The oxidation of hydrazobenzene by molecular oxygen in the polar solvent methanol is catalysed by a Schiff's base complex Co(3MeOsalen) which is a synthetic oxygen carrier. The products are trans-azobenzene and water. The rate of the reaction has been studied spectrophotometrically and the rate law established. A mechanism involving a ternary complex of catalyst, hydrazobenzene and molecular oxygen has been proposed. The kinetic studies show that a ternary complex $CoL{\cdot}H_2AB{\cdot}O_2$ is involved in the rate determining step. The reactions are summarised in a catalytic cycle. The kinetic data suggest that a ternary complex involving Co(3MeOsalen), triphenyl-phosphine and molecular oxygen is catalytically acive species but at higher triphenylphosphine concentrations the catalyst becomes inactive. The destruction of the catalytic activity could be due to the catalyst becoming coordinated with triphenyl phosphine at both z axis sites of the complex e.g. Co (3MeOsalen)$(PPh_3)_2$.