• Proceedings of the Korean Magnestics Society Conference
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• 2011.06a
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• pp.13-14
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• 2011

• 한국초전도학회:학술대회논문집
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• v.12
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• pp.19-19
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• 2002

• Proceedings of the Materials Research Society of Korea Conference
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• 1998.08a
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• pp.130.1-130
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• 1998

• Proceedings of the Materials Research Society of Korea Conference
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• 1998.08a
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• pp.42.1-42
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• 1998

• The Korean Journal of Petroleum Geology
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• v.3 no.1 s.4
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• pp.28-39
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• 1995

The objective of this study is to investigate the origin of the dolomite in the Pungchon Formation of the Choseon Supergroup near Taebaeg City, Kangwondo, Korea. The Pungchon Formation is composed of limestone, dolomitic limestone, and dolomite with thin beds of flat pebble conglomerate (FPC) and mudrock. Texturally, the dolomite in the Pungchon Formation can be divided into four types; 1) coarse-sized, xenotopic dolomite in massive dolomite, 2) medium-siEed, idiotopic dolomite in flat pebble conglomerate, 3) xenotopic dolomite replacing ooids, algalnodules, and echinoderms, and 4) the dolomite in mottled fabric. The dolomite in mottled fabric can be subdivided into three types; a) coarse-sized, xenotopic saddle dolomite cement, b) medium-sized, idiotopic, cloudy-centered, clear-rimmed (CCCR) dolomite, and c) coarse-sized, idiotopic dolomite. The carbon isotopic composition of the Pungchon dolomite is in the range of $-2.8-1.4\%_{\circ}(PBD)$, suggesting that the carbon isotopic composition was buffered by the preexisting marine carbonates. Lighter oxygen isotopic values ($\delta^{18}O-15.7-8.7\%_{\circ}, PBD$) indicate that the Pungchon dolomite may have formed under high temperature in a burial diagenetic environment. The higher initial $^{87}Sr/^{86}Sr$ ratio of the Pungchon dolomite (0.7010-0.7161) than that of the coeval Cambrian seawater (0.7088-0.7092) indicates that dolomitizing fluids had been modified from the isotopic exchange with continental crust. Low Sr and Na contents(<200 ppm) of dolomite agree well with previously reported data for burial dolomite. Hifh Fe and Mn contents of the dolomite support the idea that the Pungchon dolomite may have formed in a deep burial diagenetic environment.

• Radiation Oncology Journal
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• v.13 no.1
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• pp.9-18
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• 1995

Purpose : A retrospective analysis was performed to investigate the proper management of maxillary sinus carcinoma. Materials and Methods : Authors analysed 33 patients of squamous cell carcinoma of maxillary sinus treated at Chonnam University Hospital from January 1986 to December 1992. There were 24 men and 9 women with median age of 55 years. According to AJCC TNM system of 1988, a patient of T2, 10 patients of T3 and 22 patients of T4 were availalbe, respectively. Cervical lymph node metastases was observed in 5 patients(N 1;4/33, N2b; 1/33). Patients were classified as 3 groups according to management method. The first group, named as 'FAR' (16 patients), was consisted or preoperative intra-arterial chemotherapy with 5-fluorouracil(5-FU;mean of total dosage;3078mg) through the superficial temporal artery with concurrent radiation(mean dose delivered:3433cGy, daily 180-200cGy) and vitamin A(50,000 IU daily), and followed by total maxillectomy and postoperative radiation therapy(mean dose;2351cGy). The second group, named as 'SR'(7 patients), was consisted of total maxillectomy followed by postoperative radiation therapy(mean dose 5920 cGy). The third group, named as 'R'(6 patients), was treated with radiation alone(mean dose;7164cGy). Kaplan-Meier product limit method was used for survival analysis and Mantel-Cox test was performed for significance of survival difference between two groups. Results : Local recurrence free survival rate in the end of 2 year was $100\%$, $50\%$ and $0\%$ in FAR, SR and R group, respectively. Disease free survival rate in 2 years was $88.9\%$, $28.0\%$ and $0\%$ in FAR, SR and R group, respectively. Overall survival rate in 2 years was $88.9\%$, $40\%$ and $50\%$ in FAR, SR and R group, respectively. There were statistically significant difference between FAR and SR or FAR and R group in their local recurrence free, disease free and overall survial rates. But difference of each survival rate between SR and R group was not significant. Conclusion : In this study FAR group revealed better results than SR or R group. In the future prospective randomized study is in need.

• Journal of the Korean Ceramic Society
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• v.38 no.11
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• pp.962-966
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• 2001

Crystal structure of PbBi$_2$Nb$_2$$O_{9}$ and $Sr_{1.2}$$Bi_{1.8}$Ta$_2$$O_{9}$ were determined by Rietveld method using neutron diffraction data in the temperature range of 300 K~1273K. Phase transition temperature were measured from the dielectric permittivitytemperature curve. The PbBi$_2$Nb$_2$$O_{9}$ showed a phase transition at about 810 K. In the Sr-excess compound $Sr_{1.2}$$Bi_{1.8}$Ta$_2$$O_{9}$ the phase transition was suppressed down to room temperature. Several structural models were tested by the Rietiveld refinement. Based on the \`R\` values and the structural parameters, the B2cb model is judged to be the most feasible one for the high temperature phase at above 810 K of the PbBi$_2$Nb$_2$$O_{9}$. The $Sr_{1.2}$$Bi_{1.8}$Ta$_2$$O_{9}$ sample was refined to show the most reliable results by the Am2m model.sults by the Am2m model.

• Journal of the Mineralogical Society of Korea
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• v.14 no.1
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• pp.31-38
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• 2001

방해석 결정 성장시 나타나는 미량금속 양이온의 분배현상을 표면침전 및 연속 결정 성장과정을 통하여 관찰하였다. A, B, C 유형의 순수한 방해석이 각각 3가지 다른 초기 농도 즉 0.02, 0.2, 0.4M의 $CaCl_2$.$2H_2$O로부터 형성되었으며 이들의 표면 형태는 합성용액의 조성과 성장 속도에 의해 조절됨을 알 수 있었다. B 유형이 표면형태가 좀더 복잡하지만 A, B 유형은 대체로 단순한{1014}면을 가진 방해석과 유사한 표면형태를 보여준다. 이에 반해 C 유형에서는 {0112}면이 주로관찰되었다. 순수한 방해석 위에 $(Ca, Me)CO_3$층의 대해 {1014}면 3 방향에 대한 전자현미분석 결과 금속이온의 특징적인 분배현상을 알수 있었다. $Mn^{2+}$ /과 $Co^{2+}$ 는 {0112} 에 수직으로 반면 $Sr^{2+ }$ /는 {1014}에 수직 또는 평행한 방향으로 선택적으로 분배되는 현상이 관찰되었다. 합성 방해석 표면 형태에 따른 금속 이온들의 분배 친화도를 Mn$^{2+}$ 이 C 유형>B 유형 >A 유형 그리고 $Co^{2+}$ 은 B 유형 >A 유형 >C 유형이다. 이들중 $Sr^{2+}$는 특히 {1014}면이 잘발달된 A유형에 더 많은 친화도를 갖는 것으로 나타났다.

• The korean journal of orthodontics
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• v.48 no.6
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• pp.377-383
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• 2018

Objective: This study was performed to investigate the effects of external tooth bleaching with flouridation on the appearance of white spot lesions (WSLs) in vitro. Methods: In total, 125 bracket-bonded bovine incisor enamel blocks with artificial WSLs were randomly divided into a control group and four treatment groups (home bleaching, home bleaching + fluoridation, in-office bleaching, and in-office bleaching + fluoridation). A spectroradiometer (SR) and digital images (DIs) were used to evaluate colorimetric parameters (Commission Internationale l'Eclairage $L^*a^*b^*$) for all specimens. Color measurements were obtained before WSL formation (T1), after WSL formation (T2), and after completion of the external tooth bleaching treatment (T3). Results: The SRbased color change after bleaching was significantly greater in the treatment groups than in the control group (p < 0.05). SR-based lightness ($L^*$) and redgreen ($a^*$) values were significantly higher at T2 than at T1 (p < 0.001), with no significant changes in yellow-blue ($b^*$) values. At T3, SR-based $L^*$ values had increased while $a^*$ and $b^*$ values had decreased in the treatment groups (p < 0.001). The DI-based color difference between the sound enamel and WSL areas (DE*DI) increased significantly from T1 to T2 in all groups (p < 0.001) and significantly decreased from T2 to T3 in the treatment groups (p < 0.001). No significant differences in ${\Delta}E^*DI$ at T3 were shown between the four treatment groups (p > 0.05). Conclusions: The findings of this study suggested that external tooth bleaching with fluoridation can alleviate the conspicuity of WSLs.

• Journal of the Korean institute of surface engineering
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• v.39 no.1
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• pp.35-42
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• 2006

In this study, the fatigue properties on the cavitation damage of the flame quenched 8.8Al-bronze (8.8Al-4.5Ni-4.5Fe-Cu) as well as the current nuclear pump impeller materials (8.8Al-bronze, STS316 and SR50A) has been investigated using an ultrasonic vibratory cavitation test. For this the impact loads of cavitation bubbles generated by ultrasonic vibratory device quantitatively evaluated and simultaneously the cavitation erosion experiments have been carried out. The fatigue analysis on the cavitation damage of the materials has been made from the determined impact load distribution (e.g. impact load, bubble count) and erosion parameters (e.g. incubation period, MDPR). According to Miner's law, the determined exponents b of the F-N relation ($F^b$ N = Constant) at the incubation stage (N: the number of fracture cycle) were 5.62, 4.16, 6.25 and 8.1 for the 8.8Al-bronze, flame quenched one, STS316 and SR50A alloys. respectively. At the steady state period, the exponents b of the F-N' curve (N': the number of cycle required for $1{\mu}m$ increment of MDP) were determined as 6.32, 5, 7.14 and 7.76 for the 8.8Al-bronze, flame quenched one, STS316, and SR50A alloys, respectively.