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        검색결과 19

        2.
        1998.08 KCI 등재 구독 인증기관 무료, 개인회원 유료
        활주선 선형을 갖는 고속어선의 저항특성을 체계적으로 연구하기 위한 제 1단계로서 단면형상 및 장-폭비와 저항특성과의 관계에 대한 실험적 연구를 수행하였다. 본 연구는 새로운 고속 활주형 어선을 개발하기 위한 초기연구로서 다음의 내용을 포함하고 있다. - 4가지 단면형상에 대한 저항 특성 - 4가지 장-폭비에 대한 저항 특성
        3,000원
        3.
        1998.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The rate constants of hydrolysis of N-tert-butyl-α-phenylnitrone and its derivatives have been determined by UV spectrophotometry at 25℃ and a rate equation which can be applied over a wide pH range was obtained. On the basis of rate equations derived and judging from the hydrolysis products obtained and general base and substituent effects, plausible mechanism of hydrolysis in various pH range have been proposed. Below pH 4.5, the hydrolysis was initiated by the protonation and followed by the addition of water to α-carbon. Above pH 10.0, the hydrolysis was proceeded by the addition of hydroxides ion to α-carbon. In the range of 4.5~10.0 the addition of water to nitrone was rate controlling step.
        4,000원
        5.
        1997.11 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Ultraviolet spectrophotometric investigation has been carried out on the rate constants for 1,3-dipolar cycloaddition of 4-substituted-3-phenyloxadiazole derivatives with dipolarophiles such as phenyl acetylene, propiolic acid methyl ester and dimethylacetylene dicarboxylate. From there, the rate constants for 1,3-dipolar cycloaddition were determined at 80, 100 and 120℃, and the reaction rates were increased with increasing temperature. From these rate constants, the values of the thermodynamic activation parameters were obtained. Some thermodynamic activation parameters such as Eα, δH*, δS* and δG* from Arrhenius equation were also calculated for the electrophilic 1,3-dipolar cycloaddition of 3-phenyloxadiazole derivatives with dipolarophiles. In order to the proposal the mechanism and reactivity of 1,3-dipolar cycloaddition reaction, the effect of substituents having various kinds of electron withdrawing or releasing groups were examinated. Considering the effect of substituents, an electron withdrawing group attached at the 4-carbon position in 3-phenyloxadiazole derivatives decreases the reaction rate because of the lack of electron density in 3-phenyloxadiazole ring.
        4,000원
        6.
        1997.05 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The synthetic method of pyrazole was performed by 1,3-dipolar cycloaddition with dipolarophile instead of the reaction between diazomethane and acetylene. The cycloaddition mechanism and reactivity of 3-phenyloxadiazole derivatives with dipolarophiles was investigated. In order to investigate the mechanism and reactivity of this cycloaddition, the effect of substituents having various kinds of electron withdrawing or releasing groups were examinated. Considering the effect of substituents, an electron withdrawing group attached at the 4-carbon position in 3-phenyloxadiazole derivatives decrease the reaction rate because of the lack of electron density in oxadiazole ring. The reaction rate of 3-phenyloxadiazole derivatives with dipolarophiles were more conveniently measured using UV than using a volumetric analysis which was used before. From the result of this study, it was that the cycloaddition was found to be a first-order reaction depending upon the concentration of 3-phenyloxadiazole only.
        4,000원
        7.
        1996.11 KCI 등재 구독 인증기관 무료, 개인회원 유료
        We have synthesized the water-insoluble chitosan derivative, N-dithiocarboxy chitosan sodium salt, through the reaction of chitosan with carbon disulfide in the presence of alkali metal hydroxide, Chitosan itself has been prepared using chitin, one of the most abundant compounds in nature, as a starting material. To elucidate this natural polymer the capacity of adsorbing heavy metal ions, we have performed adsorption experiments using chitosan derivatives of various average molecular weights with different contents of sulfur. The effect of pH, adsorption time and temperature on adsorption efficiency was also studied. The adsorbent derived from chitosan of average molecular weight ranging 5,700~20,000 was shown to have the highest capacity of adsorbing heavy metal ions. Adsorbing efficiency was increased as the reaction time was increased and as the reaction temperature range of 25~45℃. The adsorption capacity at various pH, however, appeared to vary depending on the heavy metal ions studied.
        4,000원
        8.
        1996.08 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Chitosan itself has been prepared using chitin, one of the most abundant compounds in nature, as a starting material. We have synthesized the water-soluble chitosan derivative, N-dithiocarboxy chitosan sodium salt, through the reaction of water-soluble chitosan with carbon disulfide in the presence of alkali metal hydroxide. To elucidate this natural polymer capacity of adsorbing heavy metal ions, we have performed adsorption experiments using the water-soluble chitosan derivative various average molecular weight and of different percent contents of sulfur. The effect of pH, adsorption time and temperature on adsorption efficiency was also studied. The adsorbent derived from water-soluble chitosan of average molecular weight ranging 9,000~120,000 was shown to have the highest capacity of adsorbing heavy metal ions. On the whole, adsorbing efficiency was increased as the reaction time goes longer and also increased as the reaction temperture goes higer in temperture range of 15℃~45℃. The adsorption capacity at various pH, however, was appeared to vary depending on the heavy metal ions studied Judging from these finding, water-soluble N-dithiocarboxy chitosan sodium salt, a derivative of a biodegradable nature polymer, is believed to be a potential adsorbent for heavy metal ions since it not only is shown to lower the concentration of heavy metal ions to below the drainage quality standard, but also it would not cause acidification and hardening of soil which is one of the detrimental effects of synthetic macromolecular adsorbents present.
        4,000원
        9.
        1996.05 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Fluorenylidene chalcone derivatives were synthesized by condensation. The structure of these compounds were ascertained by means of UV, melting point, IR and 1H-NMR spectra. The nucleophilic addition reaction kinetics of Thioglycolic acid to fluorenylidene chalcone was investigate by UV in 20% dioxane-H2O at 25℃. The rate equation which were applied over a wide pH1.0~13.0 range. On the basis of general base catalysis and confirmation of addition reaction product, the nucleophilic addtion reaction kinetics of thioglycolic acid to fluorenylidene chalcone were measured by the pH change. From the result of the above caption, a plausible nucleophilic addition reaction mechanism of thioglycolic acid to fluorenylidene chalcone was proposed. These compounds may be used as the starting materials for the preparation of the engineering plastics or the germicide.
        4,000원
        10.
        1996.05 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Furfurylidene acetophenone derivatives were synthesis, it was measured that hydrolysis made use of UV at a wide pH 1.0~13.0 range in 30% dioxane-H2O solution, 25±1℃. On the basis of general base catalysis, substitutent effect, confirmation of hydrolysis products, it was measured the reaction rate of furfurylidene acetophenone derivatives for the pH change. It maybe concluded that a part was unrelated to pH and another part was in proportion to concentration of hydroxide ion : Above pH 10.0, It was in proportion to concentration of hydroxide ion, a part having no concern with pH was added to the neutral H2O molecule. From the result of measurement the reaction rate, hydrolysis of furfurylidene acetophenone derivatives confirmed to the irreversible first order. Through measurement the substituent effect, It found that reaction rate was accelerated by electron attracting group. Also, From the result of final product, There were furfural and acetophenone. On the basis of these findings, Hydrolysis for the furfurylidene acetophenone derivative was proposed a fitting mechanisms.
        4,000원
        11.
        1995.11 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Phenylvinylsulfone derivatives were synthesized by Kirners condition. The structure of these compounds were ascertained by means of ultraviolet, melting point, IR and 1H-NMR spectra. The nucleophilic addtion reaction kinetics of L-cysteiene for phenylvinylsulfone was investigated by ultraviolet spectrophotometery in 40% EtOH-H2O at 25℃. The rate equations which were applied over a wide pH 1.0~13.0 range. On the basis of general base catalysis and confirmation of addtion reaction product, the nucleophilic addtion reaction kinetics of L-cysteiene for phenylvinylsulfone were measured by the pH change. From the result of the above caption, a plausible nucleophilic addtion reaction mechanism of L-cysteiene for phenylvinylsulfone was proposed. These compounds may by used ad the starting materials for the preparation of the engineering plastics or the germicide.
        4,000원
        12.
        1995.11 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The rate constant of Nucleophilic addition of sodium thiophenoxide to nitrone were determined by UV Spectrophotometry and a rate equation which can be applied over wide pH range was obtained. Base on the rate equation, general base effect, substituent effect and final product, plausible mechanism of addition reaction have been proposed. Blow pH 3.0, the reaction was initiated of thiophenol, and in the range of pH 3.0~10.0, proceeded by the competitive addition of thiophenol and thiophenoxide anion. Above the pH 10.0, the reaction proceeded through the addition of a thiophenoxide anion.
        4,000원
        13.
        1995.11 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The rate constant of the nucleophilic addition of 1-propanethiol to α-phenyl-N-iso-propylnitrone derivatives were determined at various pH and a rate equation which can be applied over wide pH range is obtained. Final product of the addition reaction was α-thiopropyl-p-phenylbenzylideneamine. Base on the rate equation, general base effect, substituent effect and final product, plausible mechanism of addition reaction have been proposed. Below pH 3.0, the reaction was initiated by the addition of 1-propanthiol, and in the range of pH 3.0-10.0, proceeded by the competitive addition of 1-propanethiol and propanethiolate. Above the pH 10.0, the reaction proceeded through the addition of propanethiolate.
        4,000원
        14.
        1991.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The kinetic of hydrolysis for cinnamylidene aniline derivatives has been investigated by ultraviolet spectrophotometry in 20% (v/v) dioxane - H2O at 25℃. A rate equation which can be applied over wide pH range was obtained. The substituent effects on cinnamylidene aniline derivatives were studied and the hydrolysis was facilitated by electron attracting group. Final products of the hydrolysis were cinnamaldehyde and aniline. From the rate equation, substituent effect and final products, the hydrolysis of cinnamylidene aniline derivatives was initiated by the neutral molecule of H2O which does not dissociate at below pH 9.0~12.0, but proceeded by the hydrogen ion at above pH 5.0~9.0.
        4,000원
        15.
        1990.11 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The Kinetics of the addition of benzalacetophenone derivatives was investigated by ultraviolet spectrophotometery in 5% dioxane H2O at 50℃. A rate equation was obtained in wide range of pH. The substituent effects on benzalacetophenone derivatives were studied, and addition were facilitated by electron attracting groups. The final product was benzalacetophenone-β-thioglycolic acid synthesized by the addition of thioglycolic acid to benzalacetophenone. On the base of the rate equation, substituent effect, general base effect and final product, the plausible addition mechanism was proposed: Below pH 9.0, only neutral thioglycolic acid molecule was added to the carbon-carbon double bond, and in the range of pH 9.0~11.0, neutral thioglycolic acid molecule and thioglycolic acid anion competitively attacted the double bond. By contrast, above pH 11.0, the reaction was dependent upon only the addition of thioglycolic acid anion.
        4,000원
        16.
        1989.11 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The Kinetics of the Hydrolysis of benzalacetophenone derivatives has been investigated by ultraviolet spectrophotometry in 5% dioxane - H2O at 50℃. A rate equation which can be applied over wide pH range was obtained. The substituent effect on the hydrolysis of benzalacetophenone derivatives were facilitated by electron attracting groups. Based on the rate equation, substituent effect, general base effect, activation parameters and final product, the hydrolysis of benzalacetophenone derivatives seems to be initiated by the netural molecule of H2O which does not dissociate at below pH 9.0 but proceeded by the hydroxide ion at above pH 11.0. In the range of pH 9.0~11.0 these two reactions occur competitively.
        4,000원
        17.
        1989.11 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The rate constants of the hydrolysis of cinnamanilide derivatives were determined UV spectrometry in H2SO4 (5~20N), NaOH(5~11N) at 50~110℃ and rate equation could be applied over a strong acid and strong base were obtained. Final product of the hydrolysis was a cinnamic acid. The σ values obtained from the slope of linear plots of log kabs vs. Hammet tΣ constants were slightly negatives, Substituents on cinnamanilide showed a relatively small effect, with hydrolysis facilitated be electron donating group. Activation energy(Ea)was also calculated for the hydrolysis of the cinnamanilide. From this reaction rate equation, substituent effect and experimental of rate constants, that the hydrolysis of cinnamanillde was Initiated by the netural molecule of H2O which do not dissociate at strong acid, and proceeded by hydroxide ion at strong base.
        4,000원
        18.
        1989.05 KCI 등재 구독 인증기관 무료, 개인회원 유료
        To developed new process for obtaining maximum molecular weight of anionic acrylamide and acrylic acid copolymer by inverse emulsion polymerization. Concentration of initiator, reducing agent, surfactant and mole ratio of acrylamide-acrylic acid were studied for the process. Semi-batch processes with method of redox, control of reaction temperature, feeding method of monomer and reaction time, was suitable for maximum molecular weight of P(AMAC) from this process obtained 3.09 × 106(Mn.) and 4.41 × 106(Mw.) in molecular weight measured by the intrinsic viscosity method. inverse emulsion polymerization mechanism of P(AMAC) does not followed the Smith-Ewart and Medvedev theory, but selected for concentration of initiator, reducing agent, surfactant, water solubility of monomer.
        4,000원
        19.
        2015.08 KCI 등재 서비스 종료(열람 제한)
        ARPA(Automatic Radar Plotting Aid)는 자동레이더 플로팅 장치로써, 레이더 물표의 상대침로와 상대방위로 구성된 운동벡터에 본선의 침로와 방위로 구성되는 운동벡터를 가감 연산(벡터연산)하여, 물표의 진침로와 진방위 및 최근접점과 근접시간을 계산하는 장치를 말한다. 본 연구의 목적은 ARPA 레이더를 구현하기 위한 물표의 획득 및 추적 기술을 개발하는 것으로, 이에 관한 여러 선행 연구를 검토하 여 적용 가능한 알고리듬 및 기법을 조합하여 기초적인 ARPA 기능을 개발하였다. 주요 연구내용으로, 레이더 영상에서 물표를 획득하기 위 하여, 회색조 변환, 가운시안 평활 필터 적용, 이진화 및 라벨링(Labeling)과 같은 순차적 영상 처리 방법을 고안하였고, 이전 영상에서의 물표 가 다음 영상에서의 어느 물표인지를 결정하는데 근접이웃탐색알고리듬을 사용하였으며, 물표의 진침로와 진방위를 계산하는 거동해석에 칼 만필터를 사용하였다. 또한 이러한 기법을 전산 구현하여 실선실험을 수행하였고, 이를 통해 개발된 ARPA의 기능이 실용상 사용가능함을 검 증하였다.