• Bulletin of the Korean Chemical Society
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• v.33 no.1
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• pp.270-274
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• 2012

The nucleophilic substitution reactions of 1,2-phenylene phosphorochloridate (1c) with X-pyridines are investigated kinetically in acetonitrile at $-25.0^{\circ}C$. The free energy correlations for substituent X variations in the nucleophiles exhibit biphasic concave upwards with a break point at X = 3-Ph. The pyridinolysis rate of 1c with a cyclic five-membered ring is $2.70{\times}10^5$ times faster than its acyclic counterpart (1a: phenyl ethyl chlorophosphate) because of great positive value of the entropy of activation of 1c (${\Delta}S^{\neq}$ = +26 eu) compared to negative value of 1a (${\Delta}S^{\neq}$= -24 eu) over considerably unfavorable enthalpy of activation of 1c (${\Delta}H^{\neq}=20.5kcal\;mol^{-1}$) compared to 1a (${\Delta}H^{\neq}=12.7kcal\;mol^{-1}$). Great enthalpy and positive entropy of activation are ascribed to sterically congested transition state (TS) and solvent structure breaking in the TS. A concerted mechanism involving a change of nucleophilic attacking direction from a frontside attack with the strongly basic pyridines to a backside attack with the weakly basic pyridines is proposed on the basis of greater selectivity parameters (${\rho}_X$ = -1.99 and ${\beta}_X$ = 0.41) with the strongly basic pyridines compared to those (${\rho}_X$ = -0.42 and ${\beta}_X$ = 0.07) with the weakly basic pyridines.

• Korean Journal of Veterinary Research
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• v.25 no.2
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• pp.175-181
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• 1985

An eighteen months old, female, Great Dane dog which had shown signs of severe cachexia, dehydration, hematuria, vomiting and the palpable cervical mass during three weeks was examined clinically and necropsied after death. Diagnosis of this tumor case was made by gross pathology, cytology of the aspirate, radiography of the abdomen and the tumor tissse as multicentric, histiocytic lymphosarcoma. Cytologic findings of the needle aspirate of the cervical lesion were typical of macrophage origin cell. The tnmor was encountered predominantly in the lymph nodes, tonsils and spleen. The predominant cell type of these tumor masses manifested characteristics of histiocytic cells.

• Journal of the Korean Society for Precision Engineering
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• v.12 no.11
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• pp.45-51
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• 1995

In order to suggest the proper cutting conditons of the CNC milling machining for the free-form surface, some experments were carried out. In the experiments, the influence of cutting conditions on a inclined spherical surface were examined by geometrical analysis. In this study, the roundness and cutting force were measured to know the effect of several cutting conditions on the machined surface and the cutting characteristics were carefully investigated. The results obtained in this study are aw follows. 1) If the tool ha s enough rigidity, we can get better dimensional accuracy in up-ward cutting than down- ward cutting. 2) A great roundness error is appeared on the surface declined under 30 degress to the horizontal plane in circular machining by a bal end mill. 3) If the thrust force is increased, the stability of tool is decreased. And the phenomenon is apperared in great in down-ward cutting than up-ward cutting.

• Journal of the Korean association of regional geographers
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• v.7 no.1
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• pp.83-95
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• 2001

The purpose of this study is to examine that we can estimate land use by land values in 5 great cities. For this purpose, I calculated the percentage that each lot value makes up of the highest land values in the city as a indicator. I think this rate is very useful in the comparative study about many cities. At first, I set up four hypotheses based on my preceding studies. Hypothesis 1, the range of CBD can be estimated as having about 10% of the peak land values. Hypothesis 2, when the peak rate of concentric circle of land values seperated from CBD circle is about 30% of the peak land values, that is sub-CBD. Hypothesis 3, generally, a lot of having about 5% of the peak land values represents residential land commercial land use. Hypothesis 4, a lot of having about 3% of the peak land values represents only residential land use. The data on land values in five great cities were got from public notification on land values(1999) of the Ministry of Construction & Transportation. I selected highest lot values from many standard lot value in each Tong(the minimum administrative unit) in each cities. And I drew land values isopleth. Through that isopleth, I identified CBD cmd sub-CBD. Through the book of public notification on land values, I identified what land use are lots of having over 10%, about 5%, below 3% of the peak land values. As a result, we identified land use can be estimated by the percentage that each lot value makes up of the highest land values in the city. The bigger urban size becomes and the more stable land use becomes, the higher fitness of hypotheses becomes. The lowest degree of fitness about 4 hypotheses among 5 great cities showed in Inchon. Because Inchon lies adjacent to the greatest Seoul. The percentage that showed the lowest degree of fitness is 5% of the highest land values. The land use on lots of having about 5% of the peak land values is different from each other according to regional character in city.

• Textile Coloration and Finishing
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• v.31 no.3
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• pp.214-224
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• 2019

This investigation reported the simulation technologies to design the 3-dimensional fabrics such as 3 dimensional multi-layered fabric, 3 dimensional braided fabric and spacer fabric. The simulation system or software has been actively used to develop products of 3 dimensional fabric which can be reduced development costs and time. Thus, many countries such as Japan, Germany, China, and U.K. show great interests on simulation technologies for developing new materials and processes including 3 dimensional fabric field. In this study, simulation systems have been reviewed for the 3 dimensional fabric design system from Mikawa Textile Research Center, Japan; ProCad and ProFab from Karl Mayer and Texion, Germany; xComposites from China; TexGen from Nottingham University, U.K.; TexPro from Young Woo CnI, Korea, respectively.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2004.04a
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• pp.252-254
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• 2004

In the past several years phytoremediation, defined as the use of plants for removing contaminants from media such as soils or water, has attracted a great deal of interest as a potentially useful remediation technology. In this study, we have attempted to asses the effectiveness of phytoremeidation of disel contaminate soils using hybrid poplar species. 3 poplar species had removed disel from soil effectively and toxic effect was also observed over 2500mg/kg disel contaminated soil, which indicating reducing disel removal.

• Journal of the Korean Operations Research and Management Science Society
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• v.3 no.2
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• pp.29-39
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• 1978

Scarcely a month passes that another paper lamenting the short-comings of either Management Information Systems (MIS) or Management Science (MS) doesn't appear in the literature. It is unfortunate that these disciplines which have been universally commended to management and which obviously have great potential, have fallen into difficult times. It is likewise unfortunate that another promising construct--the corporate model--will likely meet a similar fater unless the present course of events is altered.

• Journal of Korean Society for Quality Management
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• v.30 no.3
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• pp.195-202
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• 2002

The problem of trend change in the mean residual life is great Interest in the reliability and survival analysis. In this paper, a new test statistic for testing whether or not the mean residual life changes its trend Is developed. It is assumed that neither the change point nor the proportion at which the trend change occurs is known. The asymptotic null distribution of test statistic is established and asymptotic critical values of the asymptotic null distribution is obtained. Monte Carlo simulation is used to compare the proposed test with previously known tests.

• Communications of the Korean Mathematical Society
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• v.33 no.3
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• pp.833-851
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• 2018

In this article, we prove some normality criteria for a family of meromorphic functions having zeros with some multiplicity. Our main result involves sharing of a holomorphic function by certain differential polynomials. Our results generalize some of the results of Fang and Zalcman [4] and Chen et al. [2] to a great extent.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.36 no.8
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• pp.539-546
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• 1987

In case of operating at Variable speed the induction motor by a frequency transformer, it will cause ripples in motor torque and considerably bad effects on the machines because the output side of the frequency transformer involves a great number of harmonics. This paper Presents the methods of decreasing torque ripples in induction motor and of improving current waveform, by means of forming the waveforms of output current into multi-step waveforms similiar to sinusoid, and also by means of eliminating the harmonic components maximally, in case of operating a 18-phase multi-inverter combining 3-step current source inverter.