• Journal of the Korean Chemical Society
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• v.52 no.2
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• pp.148-154
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• 2008

A simple and fast method for extraction and determination of trace amounts of copper(II) ions using octadecyl-bonded silica membrane disks modified with 2-propylpiperidine-1-carbodithioate (PPCD)I and atomic absorption spectrometry (AAS) is introduced. Extraction efficiency and the influence of flow rates, pH, and type and smallest amount of stripping acid were investigated. Maximum capacity of the membrane disks modified with 2 mg of the anthraquinone derivative used was found to be 425μg Cu2+. The limit of detection of the proposed method is 7 ng/ml. The method is applied to the recovery of Cu2+ from different synthetic samples and a spring water sample.

• The Research Journal of the Costume Culture
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• v.7 no.2
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• pp.211-219
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• 1999

The purpose of this study was to trace and identify termilogies recorded im kei lim yu sa. ma(麻), kyun(絹), po(布), je(苧), and je-po(苧布) were included in this study. For the analysis of this research comparative analytical methods was employed. Some significant findings and results of this study can be summarized as follows : 1. Text : hemp is called san(麻曰三). The word san of Koryo was derived from Indian sann, san, sana, sunn, 2. Text : Kyun is called jyi or kib(絹曰及). The word jyi(及) of Koryo was from jyi or kib() of Silla. 3. Text : Hemp cloth is called bey(bei), pey(pei), bai(布曰背). Be (베) has two meanings of hemp cloth and cloth in Korean. In the text it is interpreted as hemp cloth. 4. Text : Ramie or China grass is called mar, maw, mao, mu (毛). (苧曰毛). It is considered that the word mau(mo in Korean) (毛) in text is correct and word mau(毛) meaning China grass of Koryho is derived from mah or mak that is an old Egyptian name for flax or linen. The word mau(mo) (毛) of Koryo seems to be a transliteration of mah(or mak) in Korean or a variety of it. 5. Raime cloth or China grass cloth is clalled mau shy (苧布曰毛施). Silmar words to mau shy(毛施) of Koryo were found in Chinese, Manchurian and japanese as well as in Ancient Hebrew.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.7 no.4
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• pp.610-618
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• 1997

$Al_2O_3$/Al composite was produced by the infiltration of molten Al Into $Al_2$O$_3$ preform at 900-$1200^{\circ}C$, The process was accelerated by spreading borosilicate glass powder onto the interface between Al powder compact and $Al_2O_3$ preform. Melt infiltration initialed after incubation period, and the growth of infiltration was observed to be linearly propotional with time. The major components of the composite are $Al_2O_3$ and Al with a trace of Si which is remained from borosilicate, the reaction accelerator. Relative density of the composite increased with the particle size of $Al_2O_3$ but decreased with infiltration temperature. As infiltration temperature increases from room to $950^{\circ}C$ higher strength and fracture toughness were obtained.

• Analytical Science and Technology
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• v.12 no.6
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• pp.521-527
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• 1999

In this study, capillary columns for ion chromatography were developed to analyze trace amount of ions in samples. When small I.D. capillary columns are used in ion chromatography, the typical flow rate of the mobile phase is $5{\sim}15{\mu}L/min$ and the typical column length is 50~150 mm. The capillary columns were made using RSL-300 fused silica capillary(I.D.: 0.53 mm, O.D.: 0.67 mm) and AG14 column resin(support : polystyrene-divinylbenzene, functional group : alkyl quaternary ammonium). The new conductivity cell and suppressor were also developed and made for capillary column ion chromatography. When several anions (fluoride, nitrite, nitrate, chlorate) were analyzed using these capillary columns, reproducible and good chromatograms were obtained.

• Journal of the Korea Computer Industry Society
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• v.5 no.1
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• pp.57-64
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• 2004

The speed gap between processors and disks is a serious problem. So, I/O sub-system limits the performance of computer system. To overcome the speed gap, caches have been used in computer system. By using cache, the access times to disk blocks can be reduced and the performance of computer system can be improved. In this paper, we proposed an efficient cache management algorithm for computer system which have buffer cache and disk cache. The proposed algorithm can minimize the duplicated blocks between buffet cache and disk cache. We evaluate the proposed algorithm by trace-driven simulation. The simulation results show that the proposed algorithm can reduce the mean access time to disk blocks.

• Journal of Chest Surgery
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• v.26 no.3
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• pp.191-195
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• 1993

Among 25 consecutive cases having undergone mitral valve surgery between March 1991 and June 1992 in Gill General Hospital, 11 patients[44%] who had undergone mitral valve reconstruction using prosthetic rings is evaluated and presented. Patients` mean age is 43 + 19 years[range:16-72], and they are consisted with 4 males and 7 females. Mitral valve insufficiency is due to degenerative disease in 6 cases[55%] and rheumatic disease in 5 patients[45%]. Carpentier`s functional classification I is 2 cases, II is 6 cases, and III is 2 cases. Surgical techniques include prosthetic ring annuloplasty[11 patients, 100%], chorda shortening[6, 55%], leaflet mobilization[4,36%], new chorda formation[2, 18%], chorda transposition[1, 9%] commissurotomy[3, 27%], and papillary muscle splitting[3, 27%]. Average number of mitral anatomic lesions per patient are 2.7 and we used average 2.8 procedures upon mitral valve apparatus per patient. There were no surgical mortality and no late valve related admission during the mean follow up period of 17 months. The mean functional class[NYHA] is 2.81 preoperatively and improved to 1.10 postoperatively. Doppler echocardiography showed much improvement from grade II MR [1 case], grade III MR [1 case] and 9 cases of grade IV MR to 6 cases of patients showed no MR, only trace MR in 4 cases, and grade I MR was found only in one patient with NYHA functional class II postoperatively. The postoperative mean mitral valve area is $2.10+0.28cm^2$. We conclude that mitral reconstruction is a predictable and stable operation.

• Journal of the Korean Society for Precision Engineering
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• v.18 no.9
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• pp.179-185
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• 2001

In this study, a visual sensor system for weld seam tracking the I-butt weld joints in GMA welding was constructed. The sensor system consists of a CCD camera, a diode laser with a cylindrical lens and a band-pass-filter to overcome the degrading of image due to spatters and arc light. In order to obtain the enhanced image, quantitative relationship between laser intensity and iris number was investigated. Throughout the repeated experiments, the shutter speed was set at 1-milisecond for minimizing the effect of spatters on the image, and therefore most of the spatter trace in the image have been found to be reduced. Region of interest was defined from the entire image and gray level of searched laser line was compared to that of weld line. The differences between these gray levels lead to spot the position of weld joint using central difference method. The results showed that, as long as weld line was within $^\pm$15$^\circ$from the longitudinal straight fine, the system constructed in this study could track the weld line successful1y. Since the processing time reduced to 0.05 sec, it is expected that the developed method could be adopted to high speed welding such as laser welding.

• Journal of Digital Contents Society
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• v.9 no.4
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• pp.653-659
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• 2008

With the recent explosion in using of the Internet, the problem of caching web objects has gained considerable importance. Caching on the Internet differs from traditional caching in several ways. Especially, the conventional caching algorithms are not well suited for the Internet caching. The poor performance is mainly due to its unfair treatment of small objects since all the objects are treated the same even though they differ in size. In this paper, I give an overview of caching policies designed for web objects, and provide a new algorithm of my own. I also have performed trace-driven simulations about variable-size replacement algorithms, and derived a new algorithm to improve byte hit-ratio by classifying objects based on their sizes.

• The Journal of Asian Finance, Economics and Business
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• v.7 no.9
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• pp.219-228
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• 2020

The study investigates the impact of inflation rate on economic growth to find the best-fit model for economic growth in Vietnam. The study applied Vector Autoregressive (VAR), cointegration models, and unit root test for the time-series data from 1996 to 2018 to test the inflation impact on the economic growth in the short and long term. The study showed that the two variables are stationary at lag first difference I(1) with 1%, 5% and 10%; trace test indicates two cointegrating equations at the 0.05 level, the INF does not granger cause GDP, the optimal lag I(1) and the variables are closely related as R2 is 72%. It finds that the VAR model's results are the basis to perform economic growth; besides, the inflation rate is positively related to economic growth. The results support the monetary policy. This study identifies issues for Government to consider: have a comprehensive solution among macroeconomic policies, monetary policy, fiscal policy and other policies to control and maintain the inflation and stimulate growth; set a priority goal for sustainable economic growth; not pursue economic growth by maintaining the inflation rate in the long term, but take appropriate measures to stabilize the inflation at the best-fitted VAR forecast model.

• Journal of the Korean Society of Tobacco Science
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• v.7 no.1
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• pp.85-92
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• 1985

Extraction efficienties of volatile organic acids in tobacco leaves according to several extraction methods were investigated and contents of volatile organic acids in 16 kinds of tobacco leaf varieties were compared. Extraction efficiency according to simultaneous distillation and extraction was 5 to 10 times higher than that according to solvent extraction, steam distillation, essential oil extraction or continuous extraction and distillation. Total contents of volatile organic acids were 1.62 to 12.94mg per l00g of sample in aromatic tobacco varieties,0.12 to 2.08mg in flue-cured tobacco leaves, and trace in burleys. Among the Korean aromatic tobacco varieties, total contents of volatile organic acids in ST374-3 were the highest, 4.66mg per l00g of sample, and those in Sohyang and Hyangcho were low, 1.69mg and 1.62mg, respectively. Among flue-cured tobacco varieties, those in NC2326 were the highest, 2.08mg per 100g of sample, but those in the other varieties were not more than 0.80mg per 1 00g of sample. Total contents of volatile organic acids in acidic hydrolysis with 0.1 M tartaric acid were higher than in non-acidic condition in all kinds of tobacco varieties.