보철용 지르코니아 어버트먼트의 표면적합도와 전기화학적 거동

박근형(K.H. Park),정용훈(Y.H. Jeong),김원기(W.G. Kim),최한철(H.C. Choe),김명수(M.S. Kim) 한국표면공학회 2009 한국표면공학회지 Vol.42 No.1

The fit between dental implant fixture and zirconia abutment is affected by many variables during the fabrication process by CAD/CAM program and milling working. The purpose of this study was to evaluate the surface compatibility and electrochemical behaviors of zirconia abutment for prosthodontics. Zirconia abutments were prepared and fabricated using zirconia block and milling machine. For stabilization of zirconia abutments, sintering was carried out at 1500℉ for 7 hrs. The specimens were cut and polished for gap observation. The gap between dental implant fixture and zirconia abutment was observed using field-emission scanning electron microscopy (FE-SEM). The hardness and corrosion resistance of zirconia abutments were observed with vickers hardness tester and potentiostat. The gap between dental implant fixture and zirconia abutment was 5~12 ㎛ for small gap, and 40~60 ㎛ for large gap. The hardness of zirconia surface was 1275.5 Hv and showed micro-machined scratch on the surface. The corrosion potentials of zirconia abutment/fixture was ?290 ㎷ and metal abutment/fixture was ?280 ㎷, whereas |Epit?Ecorr| of zirconia abutment/fixture (172 ㎷) was higher than that of metal abutment/fixture (150 ㎷). The corrosion morphology of metal abutment/fixture showed the many pit on the surface in compared with zirconia abutment/fixture.

Ti-30Ta-(3~15)Nb 합금에 HA/Ti 복합 코팅한 표면의 교류임피던스 특성

정용훈(Y. H. Jeong),이호종(H. J. Lee),문영필(Y. P. Moon),박근형(G. H. Park),장승현(S. H. Jang),손미경(M. K. Son),최한철(H. C. Choe) 한국표면공학회 2008 한국표면공학회지 Vol.41 No.5

A.C. impedance properties of HA/Ti compound layer coated Ti-30Ta-(3~15)Nb alloys have been studied by electrochemical method. Ti-30Ta binary alloys contained 3, 7, 10 and 15 wt% Nb were manufactured by the vacuum furnace system. And then specimen was homogenized at 1000℃ for 24 hrs. The sample was cut and polished for corrosion test and coating. It was coated with HA/Ti compound layer by magnetron sputter. The non-coated and coated morphology of Ti alloy were analyzed by X-ray diffractometer (XRD), energy X-ray dispersive spectroscopy (EDX) and filed emission scanning electron microscope (FE-SEM). The corrosion behaviors were investigated using A.C. impedance test (PARSTAT 2273, USA) in 0.9% NaCl solution at 36.5±1℃. Ti-30Ta-(3~15 wt%)Nb alloys showed the α+β phase, and β phase peak was predominantly appeared in the case of increasingly Nb contents. The microstructures of Ti alloy were transformed from needle-like structure to equiaxed structure as Nb content increased. From the analysis of coating surface, HA/Ti composite surface uniformed coating layer with 750 ㎚ thickness. The growth directions of film were (211), (112), (300) and (202) for HA/Ti composite coating on the surface after heat treatment at 550oC, whereas, the growth direction of film was (110) for Ti coating. The polarization resistance (Rp) of HA/Ti composite coated Ti-alloys were higher than those of the Ti and HA coated samples in 0.9% NaCl solution at 36.5±1℃. Especially, corrosion resistance of Ti-Ta-Nb system increased as Nb content increased.

다양한 유사체액과 인공타액에서 치과용 임플란트의 전기화학적 특성

김태한(T. H. Kim),박근형(G. H. Park),손미경(M. K. Son),김원기(W. G. Kim),장승현(S. H. Jang),최한철(H. C. Choe) 한국표면공학회 2008 한국표면공학회지 Vol.41 No.5

Titanium and its alloy have been widely used in dental implant and orthopedic prostheses. Electrochemical characteristics of dental implant in the various simulated body fluids have been researched by using electrochemical methods. Ti-6Al-4V alloy implant was used for corrosion test in 0.9% NaCl, artificial saliva and simulated body fluids. The surface morphology was observed using scanning electron microscopy (SEM) and energy dispersive x-ray spectroscopy (EDX). The electrochemical stability was investigated using potentiosat (EG&G Co, 263A). The corrosion surface was observed using scanning electron microscopy (SEM). From the results of potentiodynamic test in various solution, the current density of implant tested in SBF and AS solution was lower than that of implant tested in 0.9% NaCl solution. From the results of passive film stability test, the variation of current density at constant 250 mV showed the consistent with time in the case of implant tested in SBF and AS solution, whereas, the current density at constant 250mV in the case of implant tested in 0.9% NaCl solution showed higher compared to SBF and AS solution as time increased. From the results of cyclic potentiodynamic test, the pitting potential and |Epit ? Ecorr| of implant tested in SBF and AS solution were higher than those of implant tested in 0.9% NaCl solution.

ZrN 및 TiN 코팅된 치과교정 용 미니나사의 표면특성과 전기화학적 거동

김신영(S. Y. Kim),문영필(Y. P. Moon),박근형(G. H. Park),조호형(H. H. Jo),김원기(W. G. Kim),손미경(M. K. Son),최한철(H. C. Choe) 한국표면공학회 2008 한국표면공학회지 Vol.41 No.5

The dental orthodontic mini-screw requires good mechanical properties and high corrosion resistance for implantation in the bone. The purpose of this study was to investigate the electrochemical characteristics of TiN and ZrN coated orthodontic mini-screws, mini-screws were used for experiment. Ion plating was carried out for mini-screw using Ti and Zr coating materials with nitrogen gas. Ion plated surface of each specimen w as o bserved with f ield emission scanning e lectron microscopy ( FE-SEM), e nergy dispersive x -ray spectroscopy (EDX), and electrochemical tester. The surface of TiN and ZrN coated mini-screw were more smooth than that of other kinds of non-coated mini-screw due to dercrease of machined defects. The corrosion current density of the TiN and ZrN coated mini-screw decreased compared to non-coated sample. The corrosion potential of TiN and ZrN coated mini-screw were higher than that of non-coated mini-screw in 0.9% NaCl solution. The pitting corrosion resistance increased in the order of ZrN coated, TiN coated and non-coated wire. Pitting potential of ZrN coated mini-screw was the highest in the other specimens.

SiC CMOS 게이트 산화막에 관한 연구

최재승(J. S. Choi),이원신(W. S. Lee),신동현(D. H. Shin),김영석(Y. S. Kim),이형규(H. G. Lee),박근형(K. H. Park) 대한전자공학회 2001 대한전자공학회 학술대회 Vol.2001 No.6

國産紅茶의 需要開發에 關한 硏究

金銅淵,愼鏞仁,鄭址炘,金??,朴根亨 全南大學校 農漁村開發硏究所 1978 農業科學技術硏究 Vol.13 No.-

1) 國産市販紅茶의 tanin, caffeine, 全窒素 含量은 外産 最高値 比較할 때 17%, 65%, 50%의 적은 양이었다. 2) 國産인스탄트 紅茶의 tannin, caffeine, 全窒素含量은 外産 最高値와 比較하여 70%, 70%, 25%이었다. 3) 試驗品 紅茶 3種의 tannin, caffeine, 全窒素含量은 外産 最高値의 47~76%, 66~86%, 96~100%로 市販紅茶나 인스탄트 紅茶보다는 훨씬 높았다. 4) 官能檢査에서 8個製品中 成分含量이 적은 國産市販紅茶가 香, 水色, 맛이 모두 가장 나빴다. 5) 試製品 紅茶의 官能檢査結果는 市販紅茶보다는 좋았으나 香, 色, 味 모두 外産에 比해 떨어진다. 6) 國産紅茶의 缺陷을 補完하기 위해 外産最高値의 製品을 15% 混合한 것도 香, 色, 味 모두 뚜렸한 向上이 없었다. 7) 試製品에 外産 最高値의 製品을 30% 混合한 것은 水色과 맛은 外産과 거의 같았으나 香만 조금 떨어졌다. 8) 5.16革命 以前에는 紅茶와 커피의 需要量이 비슷하였는데 그후 커피의 需要量은 增加하고 紅茶만의 需要量은 漸減하고 紅茶의 需要量은 減少해 왔다. 9) 1967年 커피의 輸入量이 44萬弗이던 것이 1976年에는 그 10倍가 넘는 587萬弗로 增加하였다. 10) 5.16 革命後 커피의 輸入을 抑制하자 紅茶의 需要가 크게 增加하였는데 그 結果는 低質紅茶의 出現으로 結局 紅茶는 그 需要者들에게 不信을 當하게 되고 紅茶에 對한 需要는 그後 減退 一路를 밟게 되었다. 11) 標本調査結果 茶房에서 顧客이 가장 많이 要求하는 것은 커피로 그것은 全顧客의 60%程度이며 가장 적게 要求하는 것은 紅茶로 그것은 1.4%에 不過하였다. 家庭에서 消費되는 茶類 또는 淸凉飮料의 消費狀況을 보면 淸凉飮料가 가장 많은데 그것은 35%程度이며 다음이 커피로 30%이고 紅茶는 2%에 불과하다. 12) 國産紅茶의 嗜好度가 낮은 要因을 標本調査에 依하여 分析한 結果 맛과 香이 나쁘다는 것이 32%, 不純物이 混合된 것 같다는 것이 5.6%였다. 13) 우리나라의 總茶園造成面積은 817ha이고 茶園農家數는113戶이다. 그중 70%에 該當하는 572ha가 全南 寶城에 造成되어 있다. 그리고 817ha中 20ha만이 慶南 統營에 造成되어 있고 나머지는 모두 全南에 造成되어 있다. 또한 817ha중 680ha(83%)가 農特事業에 依하여 造成된 것이다. 14) 標本調査結果 ha當 生葉採取量은 1,577kg으로 外國에 比해 적은 水準이었다. 15) 1980年度의 生葉採取 可能量은 429,470kg으로 推定되였으며 紅茶의 最大生産 可能量은 約 100M/T으로 推定되었다. 이는 現生産量의 2倍가 넘는다. 16) 標本調査結果 茶園農家의 戶當平均 所得은 12,722원이였다. 그리고 戶當 純收益은 -415,969원이고 ha當 純收益은 -165,249원으로 赤子를 示顯하였다. 17) 茶園經營으로 因한 負債는, 戶當 平均 131,000원인데 이중 農特資金이 119,500원이다. 18) 現在 施設되어 있는 一次 및 二次加工處理工場의 施設은 모두가 낡고 在來式의 粗雜하고 零細한 國産 組立品으로 品質이 좋은 製品生産이 어려운 實情이다. 紅茶의 質ㅇ은 處理過程의 技術과 施設如何에도 많은 影響을 받는다. 近代的인 施設을 갖추자면 적어도 7,000萬원~1億원의 資金이 所要되는데 紅茶需要의 展望이 不透明한 現 狀態에서는 새로운 投資를 期待할 수는 없다. 19) 紅茶의 出開度가 30%~40%에서 採取할 때 紅茶의 品質이 가장 優秀하다. 그러나 農民들은 收買價格에 依한 損失을 補塡하려한다. 出開度가 높을수록 生産量은 增大되기 때문이다. 20) 今年度의 收買價格은 kg當익 100원이었다(出開度 90%程度). 質이 優秀한 狀態인 出開度 30~40%의 生葉을 적어도 kg當 450원의 收買價格이 要望되고 있다. 21) 流通過程에 在庫로 積在되어 있는 半製品 내지 完製品의 紅茶는 70餘M/T으로 推定된다. 이들은 모두가 品質이 낮고 變質되어 가고 있는 것으로 紅茶需要開發에 癌的存在가 되고 있다. 22) 紅茶의 製造原價를 計算해 본 結果 Tea Bag 1個當(2g入) 10원28錢이었다. 23) 紅茶의 推定損益을 計算한 結果 1期當 10 ton의 紅茶를 製造하여 모두 販賣한다고 假定할 때 損益分岐點(Black even point)은 Tea Bag 1個當 15원 이었다. The experiments and investigations were carried out for the research for the consumption promotion of Korean domestic tea. The results obtained were as follows. 1. The contents of tannin, caffeine, total nitrogen of the present domestic tea were 17%, 65%, 50% respectively as compared with those of the best foreign-made tea. 2. In case of domestic instant tea, the contents of tannin and caffeine were 70% of foreign-made tea, but total nitrogen content was only 25% of it. 3. The domestic tea which has comparatively low contents of tannin, caffeine and total nitrogen got the lowest scores in flavor, color and taste from the sensory test of 8 kinds of tea. 4. The quality of our laboratory-made tea was better than that of the domestic tea, but unfortunately worse than the. foreign-made tea in flavor, color and taste. 5. The tea which was supplemented with 30% of best foreign made tea to our laboratory-made tea had nearly same quality with foreign-made tea in color and taste, but some-what inferior in flavor. 6. The total amount of coffee import was 440 thousand dollars in 1967, but that import was increased to 5870 thousand dollars (more than 10 times) in 1976. 7. According to the sample survey method, about 60% of custormer in the tea-room preferred a cup of coffee. On the contrary, 1.4% of custormer ordered a cup of tea. Also from a view of consuming pattern at home, a soft drink was most favorite one as 35% and then 30% of coffee, but in case of tea, the figure dropped to 2%. 8. The total tea planted acreage is 817ha and total tea farming house is 113. Among these 70% of total-acreage, 572ha is built up in Bosung area, Chonnam. 9. Actual yield of tea leaf per ha is 1577kg; This indicates a low productivity as compared with that of foreign country. 10. The expected yield of tea leaf in 1980 is considered as 429,470kg and maximum possible amount of tea production will be expected about 100% as twice as present output.

한국산 다엽(茶葉)의 특수성분에 관한 연구

김동연,정지흔,김관,이종욱,박근형 한국농화학회 1979 Applied Biological Chemistry (Appl Biol Chem) Vol.22 No.2

Tea leaves were harvested from the two cultivating sites in May, July and September. Tannin and caffeine, main factors for the quality of tea products, were analyzed and compared with the wild tea leaves and the cultivated. Aroma components of two varieties of tea leaves harvested in September were analyzed by gas-chromatographic method. The results obtained were as follows. 1. Tannin contents were 10-14% same as Chinese tea variety and increased gradually to September and showed no difference between the wild tea leaves and the cultivated. 2. Caffeine contents were 1.5-3% same as other Chinese variety and showed no difference between the wild tea leaves and the cultivated. 3. Aroma components showed nearly similar patterns between two different tea varieties and were identified as phenol, iso-butyl aldehyde, n-butyl aldehyde, iso-valer aldehyde, n-butyl alcohol, iso-amyl alcohol, iso-valeic acid, benzaldehyde, n-valeric acid and linalool among 32 peaks.