• 한국수소및신에너지학회논문집
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• 제30권2호
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• pp.103-110
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• 2019

Cu-Zn-Al catalysts were prepared via co-precipitation method for low-temperature water-gas shift (LT-WGS) reaction under practical reaction condition. Aging time was systematically changed to find optimum point for LT-WGS under practical condition. The Cu-Zn-Al catalyst aged for 72 hours showed the highest CO conversion within low-temperature range as well as very stable catalytic activity for 200 hours despite the practical reaction condition.

• 기본간호학회지
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• 제1권2호
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• pp.173-191
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• 1994

This descriptive-correlational study was conducted to exam if there were relation between noise level and reaction to noise of inpatient. The purpose of this study was to provide a basic data for comfort of patient hospitalized. The hypotheses of the study are : 1. The higher perceived noise level of inpatient, the higher reaction level to noise. 2. The higher perceived noise level of inpatient, physiological reaction level to noise. 3. The higher perceived noise level of inpatient, the higher emotional reaction level to noise. The participant were 153 patients hospitalized in one general hospital. The research instruments used for this study were noise scale and reaction of patient scale developed by the author. Data was collected over a period of 10 days from the 9th of July to the 18th of July, 1994. Statistical analysis of the data included percentage, t-test, ANOVA and Scheffe test. Examination of the hypotheses was done by use of pearson correlation coefficient. The results are summarized as follows ; 1. The mean score of noise level was 2.24. Among noise factors reported by the subjects, that which ranked highest was 'Conversation of Visitors'(2.82). Next were 'noise of handling receptacle'(2.73), 'the others noise from outside'(2.73) and 'Conversation of supporter'(2.71). 2. The mean score of reaction level to noise was 2.19, physiological reaction level 2.04 and emotional reaction level 2.37. Among Physiological reaction to noise reported by the subjects, that which ranked highest was 'tired'(2.39). Next were 'sweating'(2.22) and 'headache'(2.20). Among emotional reaction to noise reported by the subjects, that which ranked highest was 'to irritate nerve'(2.53). Next were 'disturbing rest'(2.51) and 'to disturb sleep'(2.46). 3. The relationship between perceived noise level of inpatient and reaction to noise was statically significant (r=0.599, p=.0001). The relationship between perceived noise level of inpatient and physiological reaction to noise was statically significant (r=0.554, p=.0001). The relationship between perceived noise level of inpatient and emotional reaction to noise was statically significant(r=0.535, p=.0001). Thus hypothese 1, 2, 3 were supported. 4. There were significant differences between noise level of inpatient, admission periods, mobility of physical condition and exposure level to noise. 5. There were significant differences between physiological reaction level to noise, admission periods, mobility of physical condition and operation Yes or No. 6. There were significant difference between emotional reaction level to noise, admission periods, mobility of physical condition and exposure level to noise.

• Preventive Nutrition and Food Science
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• 제22권1호
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• pp.37-44
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• 2017

Sulfur-containing amino acids play important roles in good flavor generation in Maillard reaction of non-enzymatic browning, so aqueous model systems of glucosamine and cysteine were studied to investigate the effects of reaction temperature, initial pH, reaction time, and concentration ratio of glucosamine and cysteine. Response surface methodology was applied to optimize the independent reaction parameters of cysteine and glucosamine in Maillard reaction. Box-Behnken factorial design was used with 30 runs of 16 factorial levels, 8 axial levels and 6 central levels. The degree of Maillard reaction was determined by reading absorption at 425 nm in a spectrophotometer and Hunter's L, a, and b values. ${\Delta}E$ was consequently set as the fifth response factor. In the statistical analyses, determination coefficients ($R^2$) for their absorbance, Hunter's L, a, b values, and ${\Delta}E$ were 0.94, 0.79, 0.73, 0.96, and 0.79, respectively, showing that the absorbance and Hunter's b value were good dependent variables for this model system. The optimum processing parameters were determined to yield glucosamine-cysteine Maillard reaction product with higher absorbance and higher colour change. The optimum estimated absorbance was achieved at the condition of initial pH 8.0, $111^{\circ}C$ reaction temperature, 2.47 h reaction time, and 1.30 concentration ratio. The optimum condition for colour change measured by Hunter's b value was 2.41 h reaction time, $114^{\circ}C$ reaction temperature, initial pH 8.3, and 1.26 concentration ratio. These results can provide the basic information for Maillard reaction of aqueous model system between glucosamine and cysteine.

• 한국생산제조학회지
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• 제22권1호
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• pp.119-124
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• 2013

In this paper, we analysed fatty acid methyl ester contents in the biodiesel which is produced from the newly developed biodiesel production equipment. The lard oil was used as the raw material through various experimental conditions. Thirty one experiments were conducted, which were based on the experimental conditions that designed by central composite design method. The effects of four independent variables, including reaction temperature, reaction time, oil to methanol molar ratio, and catalytic amount, were investigated at five levels using central composite design (CCD). Fatty acid methyl ester content was chosen dependent variable. Although the results of analysis of the surface with an irregular surface geometry showed that the biodiesel was partially impure after the reaction due to the natural characteristics of the lard oil as the raw material, we could confirm the relationship between them from the facts that the production amount of fatty acid methyl ester changes according to reaction temperature, reaction time, oil to methanol molar ratio, and catalytic amount.

• 한국가스학회지
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• 제18권4호
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• pp.27-34
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• 2014

본 연구에서는 단열열량계의 일종인 폭발열량 측정장치를 이용하여 레졸수지 합성반응에서 온도조절 물질이 열폭주 특성에 미치는 영향을 평가하고, 반응열과 활성화에너지 등의 속도론적 데이터를 검토하였다. 그 결과, 온도조절 물질이 투입된 낮은 고형분 농도에서는 폭주반응의 격렬함을 나타내는 순간 특성치들이 감소했다. 그러나 투입된 온도조절 물질의 갑작스런 소실은 급격한 2차 폭주반응을 촉발시켰다. 이때, 레졸수지 합성반응의 폭주반응에 의한 반응열은 페놀을 기준으로 약 157 kJ/mol이었고, 활성화에너지는 약 60 kJ/mol로 나타났다.

• 한국세라믹학회지
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• 제35권11호
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• pp.1190-1196
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• 1998

Ultrafine ${\beta}$-SiC powders were synthesized by the vapor phase reaction of TMS[Si(CH3)4] in hydrogen The reaction temperature and TMS concentration were varied from 1000 to 1400$^{\circ}C$ and from 1 to 10% respectively. The average particle size and phase of the powders were analyzed by TEM and XRD. Ultrafine ${\beta}$-SiC powders were synthesized above 1000$^{\circ}C$ and the crystallinity of the powders increased with increasing reaction temperature. Shape of the particles were spherical and had average size of about 20 nm which showed no difference as the reaction temperature and TMS concentration increased. From the FT-IR analysis the absorption bands of Si-C of the powders shifted to higher wavenumber as the reaction temperature increased,. Under the condition of total gas flow above 1500cc/min ${\beta}$-SiC and poly-Si powders were obtained simultaneously. The Si-O bond intensity was increased under the condition of total gas flow rate above 1000cc/min which might be due to oxidation formed on poly-Si.

• Journal of the Korean Wood Science and Technology
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• 제30권3호
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• pp.1-11
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• 2002

This study was conducted to investigate the effects of reaction pH conditions and hardener types on the reactivity, chemical structure and adhesion performance of UF resins. Three different reaction pH conditions, such as traditional alkaline-acid (7.5 → 4.5), weak acid (4.5), and strong acid (1.0), were used to synthesize UF resins which were cured by adding three different hardeners (ammonium chloride, ammonium citrate, and zinc nitrate) to measure adhesion strength. Fourier transform infrared (FT-IR) and carbon-13 nuclear magnetic resonance (¹³C-NMR) spectroscopies were employed to study chemical structure of the resin prepared under three different reaction pH conditions. Adhesion strength of the resins cured with three different hardeners was determined with lap shear specimens in tension. The gel time of UF resins decreased with an increasing in the amount of both ammonium chloride and ammonium citrate added in the resins. However, the gel time increased for zinc nitrate. Both FT-IR and ¹³C-NMR spectroscopies showed that the strong reaction pH condition produce uronic structures in UF resin, while both alkaline-acid and weak acid conditions produce quite similar chemical species in the resins. The maximum adhesion strength was occurred with the resin prepared under strong acid pH condition. However, this study indicated that the weak acid reaction condition provide a balance between increasing resin reactivity and improving adhesion strength of UF resin. The measurement of formaldehyde emission from the panels bonded with the UF resins prepared is planned for future work.

• KSBB Journal
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• 제26권3호
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• pp.193-198
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• 2011

Polyester was prepared through the esterification reaction between watsepaper liquefied by ethylene glycol and carboxylic acid. Liquefaction was carried out at the previously determined condition of 100 minutes, $160^{\circ}C$, and 3% sulfuric acid, and the hydroxyl value of the liquefied product was 411 mg KOH/g. In order to remove bubbles produced during the curing step, the method to introduce a slight nitrogen stream into reaction vessel and/or the method to preheat a polyester film at $85^{\circ}C$ before curing step were used alone or in combination. But if curing temperature was $130^{\circ}C$, simple method to cure a film for 5 hours at $130^{\circ}C$ without using both methods was found to be most effective. The polyesters prepared with various carboxylic acids showed significant different physical properties, and maleic acid was best among them. Also, the effect of reaction time and temperature, C/H (carboxyl group/hydroxyl group) ratio, and type of additive on the crosslinkage of polyester was investigated. Lithium hydroxide or citric acid as additive was used to enhance the crosslinkage of polyester and citric acid was proved to be much more effective than lithium hydroxide. The effect of reaction temperature on the crosslinkage was marginal, but the crosslinkage decreased above $130^{\circ}C$. The crosslinkage was 86% when the polyester was prepared at an optimum condition such as $130^{\circ}C$ and 15 minutes of reaction condition, 1.5 of C/H ratio, $130^{\circ}C$ and 5 hours of curing condition, and 10% addition of citric acid.

• 약학회지
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• 제44권1호
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• pp.36-40
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• 2000

The photodegradation of pefloxacin, photolabile fluoroquinolone antibacterial agent, was studied. In the presence of $N_2$, photodegradation of pefloxacin was suppressed. The singlet oxygen and free radical generated in the reaction media proceeded photochemical reaction. The photodegradation of peflxacin was sensitized by benzophenone, a triplet state sensitizer.

• Korean Journal of Mathematics
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• 제16권4호
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• pp.457-470
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• 2008

This paper is concerned with the robust boundary control of the chemotaxis reaction diffusion system. That is, we show that the existence of the saddle point for the robust control problem when the control and the disturbance are given by the boundary condition.