• MALSORI
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• no.63
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• pp.47-66
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• 2007

This study aims at exploring the degree of phonetic similarity between Korean and Japanese vowels in terms of acoustic features by performing the speech production test on Korean speakers and Japanese speakers. For this purpose, the speech of 16 Japanese speakers for Japanese speech data, and the speech of 16 Korean speakers for Korean speech data were utilized. The findings in assessing the degree of the similarity of the 7 nearest equivalents of the Korean and Japanese vowels are as follows: First, Korean /i/ and /e/ turned out to display no significant differences in terms of F1 and F2 with their counterparts, Japanese /i/ and /e/, and the distribution of F1 and F2 of Korean /i/ and /e/ in the distributional map completely overlapped with Japanese /i/ and /e/. Accordingly, Korean /i/ and /e/ were believed to be "identical." Second, Korean /a/, /o/, and /i/ displayed a significant difference in either F1 or F2, but showed a great similarity in distribution of F1 and F2 with Japanese /a/, /o/, and /m/ respectively. Korean /a/ /o/, and /i/, therefore, were categorized as very similar to Japanese vowels. Third, Korean /u/, which has the counterpart /m/ in Japanese, showed a significant difference in both F1 and F2, and only half of the distribution overlapped. Thus, Korean /u/ was analyzed as being a moderately similar vowel to Japanese vowels. Fourth, Korean /${\wedge}$/ did not have a close counterpart in Japanese, and was classified as "the least similar vowel."

• Journal of Navigation and Port Research
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• v.27 no.4
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• pp.359-366
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• 2003

The paper describes on the construction and analysis of marine casualty numerical D/B (N-D/B) to implement Korean MArine Casualty Forecasting System (K-MACFOS). The main target of K-MACFOS is to broadcast the prediction number and risk level of marine casualties as like daily weather forecasting. The data relating to a total of 724 ship casualties in the west-southern sea area (33oN∼35oN, 124oE∼127oE) of Korean peninsula for 11 years (1990∼2000) have been compiled and converted into quantitative data with 14 numeric conversion scales. Through the statistical analysis using contour-map visualization, the usability of N-D/B and the casualty features of the target sea areas are discussed. In addition, the optimum year-band selection method is also proposed to provide correct N-D/B analysis and precise prediction of the number of marine casualties.

• Ocean and Polar Research
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• v.31 no.1
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• pp.51-61
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• 2009

In this study we define the two different types of El $Ni{\tilde{n}}o$, i.e., the eastern Pacific El $Ni{\tilde{n}}o$ (i.e., EP-El $Ni{\tilde{n}}o$) versus the central Pacific El $Ni{\tilde{n}}o$ (i.e., CP-El $Ni{\tilde{n}}o$), during the boreal summer (June-July-August, JJA) and winter (December-January-February, DJF) using the two NINO indices in the tropical Pacific. The two different types of El $Ni{\tilde{n}}o$ significantly differ in terms of the location of the maximum anomalous sea surface temperature (SST) in the tropical Pacific. The CP-El $Ni{\tilde{n}}o$ has been observed more frequently during recent decades compared to the EP-El $Ni{\tilde{n}}o$. In addition, our analysis indicates that the statistics of CP-El $Ni{\tilde{n}}o$ during JJA is closely associated with the warming trend in the central equatorial Pacific. We also examine the different responses of the East Asian marginal SST to the two types of El $Ni{\tilde{n}}o$ during JJA and DJF. The CP-El $Ni{\tilde{n}}o$ during both JJA and DJF is concurrent with warm SST anomalies around the Korean Peninsula including the East China Sea, which is in contrast to the EP-El $Ni{\tilde{n}}o$. Such different responses are associated with the difference in tropics/mid-latitude teleconnections via atmosphere between the two types of El $Ni{\tilde{n}}o$. Furthermore, our results indicate that atmospheric diabatic forcing in relation to the precipitation variability is different in the tropical Pacific between the EP-El $Ni{\tilde{n}}o$ and the CP-El $Ni{\tilde{n}}o$.

• Journal of KIISE
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• v.43 no.11
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• pp.1216-1222
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• 2016

The advent of large-scale web services has resulted in gradual increase in the amount of data used in those services. These big data are managed efficiently by DBMS such as MySQL and MariaDB, which use InnoDB engine as their storage engine, since InnoDB guarantees ACID and is suitable for handling large-scale data. To improve I/O performance, InnoDB caches data and index of its database through a buffer pool. It also supports multiple buffer pools to mitigate lock contentions. However, the multiple buffer pool scheme leads to the additional data consistency overhead. In this paper, we analyze the overhead of the multiple buffer pool scheme. In our experimental results, although multiple buffer pool scheme mitigates the lock contention by up to 46.3%, throughput of DMBS is significantly degraded by up to 50.6% due to increased disk I/O and fsync calls.

• Proceedings of the Plant Resources Society of Korea Conference
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• 2002.11b
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• pp.68-68
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• 2002

아열대성 식물 4종 (문주란, Crinum asiaticum var. japonicum; 박달목서, Osmanthus insularis; 죽절초, Chloranthus glaber; 파초일엽, Asplenium antiquum)을 대상으로 자연 환경요인의 변화에 따른 엽록소형광을 분석하여 이들 식물의 활력도를 검토하였다. 여름철 일변화에 있어서 양지에 자라는 문주란과 박달목서는 Fv/Fm이 새벽과 밤에는 0.80~0.83 범위의 높은 값을 보이지만, 낮시간에는 0.65~0.73으로 낮았다. 1-qN과 1-qP도 낮시간에 크게 낮아졌다. 음지에 자라는 죽절초와 파초일엽의 Fv/Fm은 높아서 0.83~0.85 범위를 유지하였으며 일변화적 특성은 관찰되지 않았다. 1-qP의 변화는 거의 관찰되지 않았으나 1-qN이 낮시간에 다소 감소하는 경향을 보여주었다. 죽절초와 파초일엽에서는 광억제가 거의 일어나지 않으나 문주란과 박달목서에서는 낮시간의 고광에 의한 광억제가 나타난다. 하지만 여기에너지의 일부를 열의 형태로 방출하여 광피해를 완화시키고 있는 것으로 보인다. 겨울철에는 Fv/Fm이 모든 종에서 0.8 이하의 값을 나타내었는데, 특히 문주란의 Fv/Fm 값은 다른 3종 보다 더 낮았다. 그리고 모든 종에서 일변화적인 특성은 관찰되지 않았다. 문주란의 1-qN은 낮시간에 다소 감소하였지만, 나머지 3종의 식물은 높은 값을 나타내었다. 그리고 l-qP는 문주란과 박달목서에서는 낮시간에 0.6 범위로 낮아졌다. 이는 종에 따라 차이가 있지만 겨울철 저온의 영향을 받은 결과로 보인다. 한편, 여름철 문주란과 박달목서의 O-J-I-P곡선은 거의 유사하며 낮에 뚜렷하게 낮았고, 죽절초와 파초일엽에서는 일변화적 특성은 두드러지지 않았다. 그리고 P $I_{NO}$ 와 SF $I_{NO}$ 가 죽절초를 제외한 3종에서 여름철 낮시간에 증가하였다. 겨울철의 O-J-I-P곡선은 모든 종에서 낮시간에 다소 낮아지지만 큰 변화는 없었다. 그리고, 문주란, 박달목서, 파초일엽에서 $\psi$o/(1-$\psi$o)가 낮시간에 다소 증가하였다. 이로부터 P $I_{NO}$ , SF $I_{NO}$ , $\psi$o/(1-$\psi$o)등의 변수는 식물의 활력도를 검정하는 지표로 활용될 가능성이 높다고 할 수 있다.

• Journal of Fisheries and Marine Sciences Education
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• v.28 no.6
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• pp.1662-1672
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• 2016

To address physicochemical factors of yellow clay for removing Cochlodinium polykrikoides blooms, the correlation of removal efficiency with mineralogical characteristics of yellow clay collected from various areas was surveyed. Yellow clay from different localities showed the wide range of chemical compositions $SiO_2$ : 43~71%, $Al_2O_3$ : 13~26%, $Fe_2O_3$ : 5~14%, MgO : 0.4~1.8%, $K_2O$ : 0.6~3.3%, L.O.I.(Loss of Ignition) : 4.5~15%. The mineral compositions of yellow clay were mainly consisted of quartz and feldspar including small amounts of kaolinite, chlorite, and Fe-oxides. The result of size analysis showed that $6{\Phi}(31{\sim}16{\mu}m)$ and $7{\Phi}(16{\sim}8{\mu}m)$ were dominated sizes. The zeta-potential were in the range of -4.1~-20.7mV(average -13.7). As increasing removal efficiency of C. polykrikoides, contents of $Al_2O_3$, $Fe_2O_3$ and L.O.I. in yellow clay increased, whereas $SiO_2$ content decreased. Furthermore, the amounts of silt mineral and small particle were high when the removal efficiency was high. According to factor analysis using principle component analysis, two components of factor 1 and factor 2 showed 79% of the total variance, which is related to cohesion and adsorption. Inducing cell lysis of C. polykrikoides by cohension and adsorption between C. polykrikoides and yellow clay.

• Journal of the Korean Chemical Society
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• v.41 no.11
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• pp.594-599
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• 1997

Lithium nickel oxide ($Li_{2x}Ni_{1-x}O$) thin films have been prepared by the RF sputtering of lithiated nickel oxide target, where the film microstructure was controlled by the sputtering atmosphere $(Ar/O_2)$ and the substrate temperature ($T_s=50/230^{\circ}C$). From the transmission electron microscopic analysis, it is found that the most porous film with the grain size of $∼80\AA$ could be fabricated under the sputtering atmosphere of $P(O_2)=8{\times}10^2$ mbar with the $$T_s$=50^{\circ}C.$ In the optical and electrochemical studies, the$Li_{2x}Ni_{1-x}O$ films exhibit a significant electrochromic property in association with the lithium insertion/deinsertion process. The amount of charge insertion ($Q_i$) and the optical density (OD) variation depend on the crystallinity of the film as well as its thickness, and for the $Li_{2x}Ni_{1-x}O$ film (170 nm thickness) prepared under $O_2$ atmosphere and $T_s=50^{\circ}C$, the OD could be increased up to ∼1.3 by the charge insertion with $Q_i=30\;mC/cm^2.$

• Journal of the Korean Chemical Society
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• v.33 no.1
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• pp.135-142
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• 1989

Methyl tert-butyl ether(MTBE) was synthesized from vapor phase reaction of methanol with iso-butylene over HZSM-5 catalysts, and effects of SiO$_2/Al_2O_3$ ratio in the HZSM-5 catalysts and reaction conditions on products distribution have been examined. Acid strength and acid type of each catalyst with different SiO$_2/Al_2O_3$ ratio were measured using pyridine adsorption followed by temperature programmed desorption(TPD) and IR analysis. Reactants and products adsorption characteristics on different acid sites have also been examined. As the SiO$_2/Al_2O_3$ ratio of HZSM-5 catalyst was increased, selectivity to MTBE was improved as a result of decrease in dimethylether(DME) formation at the strong acid sites. Conversion and selectivity to MTBE were also greatly enhanced as $i-C_4H_8/CH_3OH$ reactant ratio was increased, and overall about 80$^{\circ}$C was adequate for the MTBE synthesis. The properties of deposited coke on spent catalysts were examined by TG, DTA and IR spectrum analysis, indicating the amount of the coke deposit in the order of HY > H-Mordenite > HZSM-5. Even if the coke deposited on H-Mordenite was little more in amount than to that on HZSM-5, the former deactivated quickly due to its non-interconnected channel structure. For HY, owing to its lange pore size, significant $i-C_4H_8$ polymerization was occured, and rapid deactivation and severe coke formation has resulted within few hours.

• Journal of Environmental Science International
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• v.22 no.6
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• pp.705-715
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• 2013

The response of the freshwater microalga Chlorella vulgaris to mercuric ion ($Hg^{2+}$) stress was examined using chlorophyll a fluorescence image analysis and O-J-I-P analysis as a way to monitor the toxic effects of mercury on water ecosystems. The levels of photosynthetic pigments, such as chlorophyll a and b and carotenoids, decreased with increasing $Hg^{2+}$ concentration. The maximum photochemical efficiency of photosystem II(Fv/Fm) changed remarkably with increasing $Hg^{2+}$ concentration and treatment time. In particular, above $200{\mu}M\;Hg^{2+}$, considerable mercury toxicity was seen within 2 h. The chlorophyll a fluorescence transient O-J-I-P was also remarkably affected by $Hg^{2+}$; the fluorescence emission decreased considerably in steps J, I, and P with an increase in $Hg^{2+}$ concentration when treated for 4 h. Subsequently, the JIP-test parameters (Fm, Fv/Fo, RC/CS, TRo/CS, ETo/CS, ${\Phi}_{PO}$, ${\Psi}_O$ and ${\Phi}_{EO}$) decreased with increasing $Hg^{2+}$ concentration, while N, Sm, ABS/RC, DIo/RC and DIo/CS increased. Therefore, a useful biomarker for investigating mercury stress in water ecosystems, and the parameters Fm, ${\Phi}_{PO}$, ${\Psi}_O$, and RC/CS can be used to monitor the environmental stress in water ecosystems quantitatively.

• Polymer(Korea)
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• v.32 no.3
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• pp.239-245
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• 2008

Block copolymers of the general formula $[(-CO-R'-CO-HN-Ar-NH-CO-R'-CO)_xNH(CH_2)_3-(Me_2SiO)_y(CH_2)_3NH_2]_n$, [n=18.00 to 1175.0] where $R'=CH_2CH(CH_2GeCl_3)$;$CH_2CHGeCl_3CH_2$; and $Ar=-C_6H_4$;$-(o.CH_3C_6H_4)_2$;$-o.CH_3OC_6H_4)_2$;$-(o.CH_3C_6H_4)$ were prepared by a polycondensation reaction of polyamide containing a pendant trichlorogermyl group and terminal acid chloride $Cl(-CO-R'-CO-NH-Ar-NH-CO-R'-CO-)_xCl$ with aminopropyl-terminated polydimethylsiloxane $H_2N(CH_2)_3(Me_2SiO)_y-(CH_2)_3NH_2]$, (PDMS). These polymers were characterized by elemental analysis, $T_g$, FT-IR, $^1H$-NMR, solid state $^{13}C$-NMR, and molecular weight determination. The thermal stability of these copolymers was examined using thermal analysis techniques, such as TGA and DSC. Their molecular weights as determined by laser light scattering technique ranged $5.13{\times}10^5$ to $331{\times}10^5\;g/mol$. These polymers display their $T_g$ in the range of 337 to $393^{\circ}C$ with an average decomposition temperature at $582^{\circ}C$.