• Proceedings of the Korean Fiber Society Conference
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• 1998.04a
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• pp.25-27
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• 1998

나프탈렌으로부터 제조된 메조페이스 핏치(NMP)와 개질된 등방성 콜타르 핏치(MCP)의 방사성을 유변학적거동에 기초해 설명하고자 시도되었다. 기본적으로, 방사성은 l/4, l/l, 4/1(wt. NMP/wt. MCP)로 블렌드비를 달리 하면서 shear rate를 증가시켰을 때 등방성의 농도가 클 경우 급격한 점도 감소로 cohesive fracture의 원인이 됨을 관찰할 수 있었고 NMP가 증가할수록 탄성에너지 값이 전형적인 고분자의 거동처럼 응답하는 tan $\delta$값의 임계점이 고주파수영역으로 이전되어 최대값을 나타내었고 임계점보다 낮은영역에서 상대적인 크기는 NMP가 증가함에 따라 작아지는 현상을 관찰할 수 있었다.(중략)

• Journal of the Korean Electrochemical Society
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• v.9 no.2
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• pp.70-76
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• 2006

Micro-droplet cell with free droplet as a micro-electrochemical technique has been limited to apply to electrochemical systems with high wetting properties such as an acidic solution and low grade stainless steels(Type 316L). By loading negative pressure to a droplet, control of droplet size, and use of hydrophobic gasket, the cell is modified to be allowed to use for electrochemical systems with high wetting properties. For giving the reliability of new cell, studies on local corrosion were conducted for three different systems-an acidic chloride solution and high chromium ferritic stainless steel, the other acidic chloride solution and type 316, and a neutral chloride solution and type 316. stainless steel. Firstly, the modified micro-droplet cell allows the anodic polarization curves in an acidic chloride solution to show the fact that the local corrosion of high chromium stainless steel near the $\alpha/\sigma$ interface is due to the Cr depleted zone. Secondly, the local anodic polarization test of type 316 L in the other acidic chloride solution can be successfully conducted in the cell. Furthermore, the local polarization curves help elucidating the corrosion of type 316 with $\delta-ferrite$ phase. Finally, the polarization curves of type 316 L in a neutral chloride solution indicates that the factor affecting the pitting corrosion resistance was inclusions rather than $\delta-ferrite$.

• Journal of Dental Rehabilitation and Applied Science
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• v.31 no.1
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• pp.20-25
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• 2015

Purpose: This study was evaluated the shade of feldspathic porcelain with various concentration of silver ion. Materials and Methods: The control group was conventional feldspathic porcelain with no silver ion, the experimental groups were the feldpathic porcelain with 5%, 10%, 20%, 30% silver ion. The number of specimens on the each group was 5. Commission Internationale de I'Eclairage (CIE) $L^*a^*b^*$ parameters were recorded twice for each specimen with a spectrophotometer (Model CM-2600d, Minolta, Japan). One-way Anova was used for statistical analysis. Results: L value was similar. a value was increasing and b value was decreasing with silver ion statistically significantly. ${\Delta}E$ was increasing according to silver ion significantly. Conclusion: The shade of feldspahtic porcelain was influenced by silver ion. Ag ion under 10% concentration is acceptable clinically.

• Economic and Environmental Geology
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• v.33 no.6
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• pp.469-489
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• 2000

The hydrogeochemical and isotopic studies on deep groundwater (below a 550 m depth from the ground surface) in the Munkyeong area, Kyeongbuk province were carried out. Two types of deep groundwater (${CO_2}$-rich groundwater and alkali groundwater) occur together in the Munkywong area. ${CO_2}$-rich groundwater (Ca-${HCO_3}$ type) is characterized by low pH (5.8~6.5) and high TDS (up to 2,682 mg/L.), while alkali groundwater (Na-${HCO_3}$ type) shows a high pH (9.1~10.4) and relatively low TDS (72~116 mg/L). ${CO_2}$-rich water may have evolved by ${CO_2}$ added at depth during groundwater circulation. This process leads to the dissolution of surrounding rocks and Ca, Na, Mg, K and ${HCO_3}$ concentrations are eniched. The low $Pco_2$ ($10^{-6.4}$atm) of alkali groundwaters seems to result from the dissolution of silicate minerals without a supply of ${CO_2}$. The ${\delta}^{18}O$ and ${\delta}^D$values and tritium data indicate that two types of deep groundwater were both derived from pre-thermonuclear meteoric water and have evolved through prolonged water-rock interaction. The carbon isotope data show that dissolved carbon in the ${CO_2}$-rich water was possibly derived from deep-seated ${CO_2}$ gas, although further studies are needed. The ${\delta}^{34}S$ values of dissolved sulfate show that sulfate reduction occurred at great depths. The application of various chemical geothermometers on ${CO_2}$-rich groundwater shows that the calculated deep reservoir temperature is about 130~$l75^{\circ}C$. Based on the geological setting, water chemistry and environmental isotope data, each of the two types of deep groundwater represent distinct hydrologic and hydrogeochemical evolution at depth and their movement is controlled by the local fracture system.

• The Journal of Korean Academy of Prosthodontics
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• v.33 no.4
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• pp.645-661
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• 1995

As the mechanical property of composite resin improved, composite resin has been widely used esthetic dentistry. In the field of esthetic dentistry, the color of prosthetic material is very important. The purpose of this study was to evaluate the color difference of specimens, by the types of alloys and gold electrodeposit. Experimental groups were as follows : Group Prec : Au-Pt alloy with no gold coating and no resin veneer. Group Semi : Pd-Ag alloy with no gold coating and no resin veneer. Group BAse : Ni-Cr alloy with no gold coating and no resin veneer. Group Gsem : Pd-Ag alloy with no gold coating and no resin veneer. Group Gbas : Ni-Cr alloy with no gold coating and no resin veneer. Group PreR : Resin veneer on the Pd-Ag alloy without gold coating. Group SemR : Resin veneer on the Pd-Ag alloy without gold coating. Group GbsR : Resin veneer on the Ni-Cr alloy with gold coating Group BasR : Resin veneer on the Ni-Cr alloy without gold coating. In this study, colors of metal surfaces and veneered resins were evaluated by the CIE $L^{*}a^{*}b$ system. The results obtained were as follows : 1. different alloy types and gold coating make the $L^{*}a^{*}b$ system. 2. The ${\Delta}E^*$ab value between groups semi and Base was less than 1.5 and there was no $a^*$ and $b^*$ value difference between groups Gsem and Gbas 3. The values of $L^*$ and $a^*$ ain groups GsemR and GbasR were so similar that the ${\Delta}E^*$ab value was as small as 0.58. 4. In resin specimens with gold coated semiprecious or base alloys showed yellower and redder deviation than the resin specimens with precious alloy. 5. The ${\Delta}E^*$ab values between goups PreR-GsemR and groups PreR-GbasR were as small as 2.68 and 2.22 respectively.

• The Journal of Korean Academy of Prosthodontics
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• v.36 no.2
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• pp.379-388
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• 1998

본 연구는 악안면보철용 실리콘의 색안정성을 연구하기 위하여 실리콘 재료로 MDX 4-4210 Silicone(Dow Coming. Midland, Mich.)과 A-2186(Factor II, Lakeside, Az)을 사용하고 Mars Violet. Golden Yellow, Red yellow, Raw Sienna등 4종의 색소(Factor II, Lakeside, Az)를 이용하여 시편을 제작한 후 1군은 섭씨5-55도에서 700회 thermocycling하였고, 2군은 10%의 비눗물(Ivory, Proctor & Gamble Inc,. Toronto, Ontario)에 담아 섭씨15-55도에서 700회 thermocycling하였다. 3군은 10%의 비눗물에 담아 75일간 실온에서 보관하였으며 4군은 실온의 암실에 75일간 보관하였다. 5군은 초여름인 6월 중순부터 75일간 햇볕이 잘드는 곳에 위치하였다. 이를 측색색차계(Model TC-6FX, Tokyo Denshoku Co., Japan)를 이용하여 측정하고 색변화를 연구한 결과 다음과 같은 결론을 얻었다. 1. $L^*$값의 경우 모든 실험군에서 대조군에 비해 유의하게 감소하였다. 2. $a^*$값의 경우 대부분의 실험군에서 증가하였으나 Raw sienna, Mars violet색소를 사용한 실험 3.4.5군의 MDX4-4210의 경우 감소하는 경향을 보였다. 3. $b^*$값은 실험1.2.3군의 경우 대부분 감소하였고 실험4.5.군의 경우에서 증가하였으나 3.4.5군의 경우에서 대부분 유의한 차이가 없었다. 4. ${\Delta}E$의 값은 실험군에서 대부분 감소하였으나 4군의 A-2186에서 증가하는 경향을 보였고 실험2군의 Red yellow, Mars violet을 사용한 MDX4-4210에서 비교적 큰 변화를 보였다. 5. $L^{\ast}$값과 a값의 변화량의 합은 A-2186의 경우에서 크게 나타났으나 ${\Delta}E$값의 변화량은 MDX4-4210에서 크게 나타났다. 6. $L^*$값의 변화량의 합은 실험4군에서 크게 나타났으며 $a^*$값은 1군에서, $b^*$값과 ${\Delta}E$값의 변화량의 합은 2군에서 크게 나타났다.

• Korean Journal of Food Science and Technology
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• v.28 no.1
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• pp.77-82
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• 1996

Antioxidative activity of the extract from Caesalpinia sappan L. by various solvent was compared with several commercial antioxidants, using the Rancimat method. AI (antioxidative index; induction period of oil containing extract/induction period of control oil) of all extracts were higher than commercial antioxidants, such as BHA, ${\delta}-tocopherol$ and ascorbic acid. The ethanol extract was fractionated by liquid liquid extraction. Ethyl acetate fraction showed higher AI than the whole crude extract. When comparing POV and TBA value of palm oil and lard containing different level of each fraction, the oxidative stability of ethyl acetate fraction at 200 ppm level on palm oil and lard were similar to that of BHT at 200 ppm level, and better than BHA, ${\delta}-tocopherol$ and control.

• The Journal of Advanced Prosthodontics
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• v.11 no.1
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• pp.16-22
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• 2019

PURPOSE. The purpose of this study was to compare the translucency and color changes of ceramic laminate veneers of different composition following glazing process. MATERIALS AND METHODS. $10mm{\times}10mm$ square specimens of 0.6 mm and 1.0 mm thicknesses were fabricated with IPS e.max Press (EM) and IPS e.max ZirPress (ZP) (n=10 per group). The color coordinates (CIE $L^*$ $a^*$ $b^*$) of the specimens were recorded with a colorimeter before and after glazing. The color changes and translucency parameter (TP) were calculated. For the comparisons with the composition and thicknesses between the 'not glazed' and 'glazed' groups, statistical analyses were done through paired T-test, independent two-sample T-test, and multiple regression analysis using SPSS 18.0 (P<.05). RESULTS. The TP of 0.6 mm EM was higher than that of 0.6 mm ZP. Total color difference (${\Delta}E^*$) between bare and glazed specimens of 1.0 mm EM was greater than that of 1.0 mm ZP with statistical significance. Following glazing, specimens from all groups showed statistically significant amount of decrease in $L^*$ and $a^*$, and statistically significant increase in $b^*$. The result of multiple regression analysis of EM and ZP showed that ${\Delta}L^*$ improved ${\Delta}E^*$. CONCLUSION. Within the limitations of present study, we conclude that translucency and color of ceramic laminate veneers change significantly after glazing process, and the nature and amount of changes vary with different compositions.

• The Korean Journal of Physiology
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• v.2 no.2
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• pp.53-61
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• 1968

Maximal oxygen debt, lactate and excess lactate were measured in 13 men with low hematocrit ratio before and after maximal exercise. Maximal exercise run was performed on a treadmill and the duration of run was 2 minutes 45 seconds in each subject. Hematocrit ratio ranged between 35 and 47%, the mean being 39.8%. The following results were obtained. 1. Maximal oxygen debt expressed on basis of body weight increased as the hematocrit ratio decreased. The correlation coefficient between the two was r= -0.770. 2. The time necessary for decreasing to 50% of total maximal $O_2$ debt(half time) became longer as the hematocrit ratio decreased. In normal men the half time was about 4 minutes and at the longest it was 12 minutes in men with the lowest hematocrit ratio. 3. The lactate concentration reached its peak value after 3 minutes of recovery. Thereafter, the time course of decrease in lactate concentration coincided roughly with that of respiratory oxygen debt curve. To reach to the resting level, however, it took longer time than that of respiratory oxygen debt. 4. Resting concentrations of lactate was 1.28 mM/l, pyruvate 0.13 mM/l and L/P ratio was 9.8. Peak value of ${\Delta}L$ after exercise reached to the value of 10.4 mM/l and ${\Delta}L/P$ reached 26.0. Peak excess lactate after exercise was 6.34 mM/l. 5. The part of oxygen debt accounted for by the oxygen equivalent of excess lactate was only 38.4%. A better relationship between lactate and oxygen debt was observed and the part of oxygen debt accounted for by the oxygen equivalent of lactate was 63.3%. 6. Peak value of lactate after maximal exercise increased as the hematocrit ratio decreased. 7. Respiratory oxygen debt of 100 ml/kg was accounted for by lactate more than 60% and only 30% was by excess lactate. 8. Excess lactate was not a good index of respiratory oxygen debt.

• YAKHAK HOEJI
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• v.42 no.3
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• pp.238-242
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• 1998

For the investigation of bioactive natural products with analgesic activity, we have evaluated various extracts of Saururi Herba (Saururaceae), which has been used in traditiona l medicine for edema, beriberi, jaundice, turbid urine, carbuncle and furuncle. The diethylether extract of this plant was found to show a significant analgesic effect on writhing syndrome in mice. Using bioactivity-guided separation of the diethylether extract, analgesic constituent, (8S, 8`R, 7R, 6`R)-2'-oxo-4,5: 4',5'-bis(methylenedioxy)-${\Delta}^{1,3,5,3'}$-8.8', 7.6', 2.O.5'-neolignan(sauchinone) was isolated and structurally identified by physico-chemical properties and spectroscopic evidences. This compound has good analgesic activity with lower toxicity, as compared to other antipyretic-analgesic drug(acetaminophen).