• Journal of the Korean Chemical Society
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• v.29 no.3
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• pp.213-219
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• 1985

The relative stability as a function of geometry in rigid cyclopropylcarbinyl cations was examined by $^{19}$F-nmr spectroscopy. 8-p-Fluorophenyl-tricyclo[3.3.1.0$^{2,7}$]octane-8-yl-(I), 9-p-fluorophenyl-tricyclo[3.3.1.0$^{2,8}$]nonane-9-yl (II), and 10-p-fluorophenyl-tricyclo[4.3.1.0$^{2,9}$]decane-10-yl cation(Ⅲ) were prepared from the corresponding carbinols in FSO$_3$H-SO$_2$ClF solution at -120$^{\circ}C$. $^{19}$F-nmr data indicate that the symmetrical bisected geometry of cyclopropane ring for ${\sigma}$-conjugation is a very impotant factor in charge delocalization. However, varied orientation of the bond angle ${\theta}$ within the bisected conformation does not affect the charge delocalization into the cyclopropane ring.

• Journal of the Korean Chemical Society
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• v.35 no.1
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• pp.90-95
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• 1991

A method for the selective syntheses of alkyl (alkoxymethyl)benzoates from halobenzyl halides by two steps in one pot process is described. In the first step, benzyl halide moiety is etherified with alkoxide anion in alcohol by Williamson ether process. In the second step, aryl halide moiety is carbonylated to give alkyl (alkoxymethyl)benzoate with alcohol, Na$_2$CO$_3$, CH$_3$I, and carbon monoxide (1 atm) in the presence of a catalytic amount of Co$_2$(CO)$_8$ in excellent yield.

• Journal of the Korean Chemical Society
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• v.39 no.4
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• pp.252-256
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• 1995

A study was carried out for the development of direct determination of antimony in high purity copper metal without preseparation. The large excess of copper seemed to be performed as the matrix modifier to enhance the absorbance of antimony in copper metal. Sensitivity enhancement of Sb was obtained at the condition of the ashing temperature of $600^{\circ}C(20s){\sim}700^{\circ}C(10s)$ rather than $1000^{\circ}C(20s){\sim}1100^{\circ}C(10s)$, and the atomization temperature of $2200^{\circ}C.$ The operating pressure of argon gas was readjusted to the optimum condition at 2.0 kg/$cm^2.$ The linearity of the Sb calibration graph could be obtained in the range of 20 ppb up to 200 ppb Sb in existence of 5,000 ppm Cu with the coefficient of variation of about 5%.

• Journal of the Korean Chemical Society
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• v.40 no.4
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• pp.254-263
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• 1996

Five cobalt(Ⅲ) complexes were synthesized from bi- or tridentate nitrogen ligands. Catalytic actions of these complexes for hydrolyses of p-nitrophenyl picolinate, p-nitrophenyl nicotinate, and p-nitrophenyl isonicotinate were investigated by a spectrophotometric method. p-Nitrophenyl picolinate showed the most senstive reaction among three substrates by these catalysts. Aquohydroxo Co(Ⅲ) complexes raised as much as 21∼40 times the rate of hydrolysis of p-nitrophenyl picolinate at pH 6.5. Activities of complexes were in the order: Co(ibpn)(OH)2(OH2) > Co(aepn)(OH)2(OH2) > Co(tn)2(OH)(OH2) > Co (bpy)2(OH)(OH2) > Co(dien)(OH)2(OH2). Catalytic hydrolysis was postulated to proceed through a intramolecular general base catalysis path which is mixed by a partial intramolecular nucleophilic catalysis.

• Journal of the Korean Magnetics Society
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• v.27 no.1
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• pp.30-34
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• 2017

In this report, we calculated the angular dependence of exchange bias ($H_{ex}$) by using single domain model in exchange coupled ferromagnetic (F)/antiferromagnetic (AF) bilayers, which results with AF thickness ($t_{AF}$) were used for the analysis of measured ones in NiFe/MnIr bilayers. Angular dependence of $H_{ex}$ calculated at $t_{AF}$ > $t_c$ showed typical unidirectional behaviors, however, calculated one at $0.5t_c$ < $t_{AF}$ < $t_c$ showed peculiar angular behaviors by fixed AF spins at specified angle near ${\theta}_H=90^{\circ}$. Angular dependence of $H_{ex}$ measured in NiFe/MnIr (20 nm) bilayers showed typical unidirectional behaviors. However, measured one in NiFe/MnIr (4 nm) bilayers showed mixed behaviors including both of unidirectional and peculiar angular behaviors, which was explained by the grain size distribution of polycrystalline MnIr.

• Journal of Korea Port Economic Association
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• v.29 no.3
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• pp.95-111
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• 2013

The purpose of this study is to draw out the trade effect of the Korea ASEAN FTA by carrying out a panel analysis. For achieving such a purpose, Panel Unit Root, Panel Cointegration Test, Pooled OLS, Hausman Test, Fixed Effect, Random effect are performed. The last 15 years's data over the period of 1997 to 2011 concentrated on the ASEAN countries such as Indonesia, Malaysia, Philippine, Singapore, Thai, Vietnam is used in this study. Major implications are summarized as following. First, our government need to maximize the effect derived from conclusion of FTA(Free Trade Agreement) in order to enhance the competitive edge through obtaining a stable foreign market. Second, it necessary for our government to improve a national system by orienting a FTA conclusion complying with WTO's product and service-related regulation.

• The Korean Journal of Malacology
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• v.10 no.1
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• pp.27-37
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• 1994

한국산 담수 또아리물달팽이과(Planorbidae)에 속하는 또아리물달팽이(Gyraulus convexiusculus),수정또아리물달팽이(Hippeutis cantori) 및 배꼽또아리물달팽이(Segmentina hemisphaerula)3종에 대한 종간 유전적 변이와 이들 상호간의 분류학적 유연 관계를 생화학적 측면에서 밝히고자 하였다. 즉, 모계유전으로 자손에 유전되고 있는 미토콘드리아 DNA(mitochondrial DNA; mt DNA)의 변이를 보기위하여 제한효소(restriction enzyme)를 처리하고 잘라진 mtDNA절편들을 상호 비교하는 restriction fragmint length polymorphism(RFLP)기법을 응용하였다. 본 실험에서 10개의 제한효소 중 CIa I, Dra I, Eco RI, Hin dIII, Kpn I및 pst I의 6개 제한효소에서 좋은 결과를 얻어 종간의 공통절편(shated fragmints)을 비교하였고, 염기분화율(nucleotide divergince rate)을 각각 측정하였다. 미토콘드리아 DNA 크기(genome size)는 또아리물달팽이가 12.08 kb, 수정또아리물달팽이가 14.4 kb, 그리고 배꼽또아리물달팽이가 12.93 kb로 관찰되었다. 염기분화율(p)는 또아리물달팽이/수정또아리물달팽이 군에서 p=12.7%, 배꼽또아리물달팽이와 상기 2종군 사이의 염기분화율은 P=56.6%여서 배꼽 또아리물달팽이류는 타 2종보다 그 분화율이 매우 높음을 알 수 있었다. 이상의 결과로 보아 분류군(taxa)의 mtDNA 변이에 의한 RELP기법이 앞으로 한국산 담수 패류 연구에 널리 응용될 수 있음이 확인되었다.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2017.05a
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• pp.228-231
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• 2017

The surface temperature of a combustor such as an aircraft engine is one of the important measuring factors related to the combustion performance. However, a conventional temperature measurement technique have a large measurement error due to a bad environment such as a combustion flame, vibration, and dust. In order to solve this problem, a technology has been developed which can measure the surface temperature of the combustor in real time using the wavelength change or attenuation time change according to the temperature of the phosphor. In this study, we developed a technique that can measure surface temperature of scram-jet combustor using phosphor thermometry. The calibration curve was obtained according to the temperature from $200^{\circ}C$ to $800^{\circ}C$ in the calibrated temperature chamber. So, we confirmed that phosphor thermometry can be used for measuring surface temperature of scram-jet combustor.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2017.05a
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• pp.672-674
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• 2017

The addition of swirl is a common technique used in premixed combustors in order to gain stability of the combustion with the improvements in mixing characteristics. recent experimental studies have observed that the addition of swirl oxidizer flow can effectively reduce the combustion instability in hybrid rocket. Investigation was continued to analyze the effect of the swirl on the internal flow of hybrid rocket engine main combustion chamber. The flow influenced by wall blowing as a representation of fuel evaporation interacts with swirling flow. Swirl angle increases, the amplitude of the combustion pressure decrease as the unstable combustion processes. These results suggest that the oxidizer swirling flow by the swirl angle causes the change of the turbulent flow characteristics inside the combustion chamber and suppresses the factors causing the combustion instability.

• Journal of the Korean Society of Marine Environment & Safety
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• v.19 no.5
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• pp.483-490
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• 2013

In this study, we analyzed AIS measured data for ten days by selecting the four main ports with many ships arriving in the national ports. The peak time congestion of the main ports, calculated by survey research, was about 3.8-5.7 times higher than the hourly average congestion. This is very different from the results of the advanced research, evaluating the marine traffic congestion of the Ulsan main port based on the existing Port-MIS statistical data, which showed a peak time congestion of about 1.7 times higher than the hourly average. This identifies the problem of distorting the traffic characteristics of the current passage. Therefore, in order to evaluate marine traffic congestion, it would be more appropriate to calculate it based on survey research, rather than Port-MIS statistical data.