치과주조용 Ti합금의 미세조직 변화

곽동주 대구보건대학 1994 대구보건대학 論文集 Vol.14 No.-

Effects of hydrogenation-dehydrogenation treatment on pure Ti and Ti-0.15pd alloy were studied. Pure Ti and Ti-0.15Pd alloy were conducted solution treatment at 950℃, respectively and then done hydrogenation dehydrogenation treatment. Then, the relationship between hydrogen treatment condition and X-ray diffraction patterns, i.e. the microstructure factor is examined. Ti-hydride precipitates mainly at α - β interface and also in α phase. Microstructure Ti alloy shows finer than that of pure titanium in hydrogenation and dehydrogenation treatments. Ti-0.15Pd alloy carried out solution treatment at 950℃, the transformation of α martensite was occured. Hydrogen absorption of Ti-0.15Pd alloy was higher than that of pure titanium. Dehydrogenation temperature in titanium alloy occured approximately at 400-562℃. Hydrogen tretment was used as a temporary alloying element modifying the microstructure of tianium in order to enhance fatigue behavior for partial denture.

방전플라즈마 해석을 통한 PDP용 ITO 투명전도막의 제작 및 특성

곽동주,조문수,박강일,임동건 한국전기전자재료학회 2003 전기전자재료학회논문지 Vol.16 No.10

In this paper, the ITO thin film, which is considered as one of the most currently used material for the high performance transparent conducting films for the PDP cell, was made in a parallel-plate, capacitively coupled DC magnetron sputtering system. Some electrical and optical properties of ITO films were investigated and discussed on the basis of glow discharge characteristics. The optimized thin film fabricating conditions of Ar gas pressure and substrate temperature were derived from the Paschen curve and glow discharge characteristics. The maximum transmittance of 89.61 % in the visible region and optical band gap of 3.89 eV and resistivity of 1.67${\times}$10$\^$-3/ $\Omega$-cm were obtained under the conditions of 300 C of substrate temperature and 10∼15 mtorr of pressure, which corresponds nearly to that of Paschen minimum.

油中部分放電을 경유한 PET 박막의 異常絶緣破壞특성

곽동주 慶星大學校 1992 論文集 Vol.13 No.2

The dc and impulse dielectric strengths of PET film are measured, using molded sphere to plane electrode configuration in transformer oil. The electric breakdown in the present test has two types of discharge paths one corresponds to the puncture without surface discharge and the other is the puncture with partial discharge in transformer oil-PET composite insulating system. These are called normal and anomalous breakdowns, respectively in this paper. The anomalous breakdown voltages with partial discharges are very important as the practical data for the insulation design of electric machine. Hence, brief interpretation about the anomalous breakdown characteristic of various PET films with different crystallinities and sample thickness is made, including also the normal breakdown. The dielectric strength at anomalous breakdown is lower than the intrinsic dielectric strength of PET film, and the anomalous breakdown occurs easily under the conditions of impulse electric fields and lower compressive stress.

Metal Crown 製作時 貴金屬 合金의 損失

곽동주 대구보건대학 1997 대구보건대학 論文集 Vol.17 No.-

This study investigated the loss of a noble alloy during the fabrication of metal crowns. In study found that an average of 29.0% weight of a noble was lost through the various laboratory procedures. The losses were generally higher with maxillary restorations and significantly higher for anterior restorations than for psterior units. The greatest amount of alloy was lost during the preparation of the facial surface for porcelain application. Weight losses resulting from (1) the casting process and cleaning of the casting (2) sprue cutting, (3) seating of the casting onto the die, and (4) preparation for porcelain addition were invested using 323 crowns. The percentage weight losses were 9.80%, l6.46%, 35.69%, and 38.05%, respectivery. Weight losses were generally higher for maxillary restoration, but metal bond porcelain restoration on anterior teeth registered significantly higher losses than those for premolars and molars.

평판형 마그네트론 스퍼터 시스템의 RF 방전특성 및 플라즈마 진단

곽동주 경성대학교 공학기술연구소 1998 공학기술연구지 Vol.5 No.-

Electrical characteristics and plasma parameters of RF discharge driven at 13.56MHz in a parallel-plate magnetron sputtering system were measured since they may be considered as the important factors deciding the thin film properties. From these measurements the interpretation on the dissipation mechanism of RF power was carried out, and the relationships between electron temperature and density as parameters of RF power and position were discussed.

구강균 Streptococcus mutans KDJ-50에 대한 정향의 향균효과

곽동주,남상용,정석민,Kwak, Dong-Ju,Nam, Sang-Yong,Chung, Suk-Min 대한치과기공학회 2001 대한치과기공학회지 Vol.23 No.1

This study was conducted to find antibacterial agent against growth of dental caries bacteria. St. mutans KDJ-50 from various medicinal plants of which safety was indetified. Medicinal plants used in this study was dried and grinded after purchased at Daegu yakryung sijang and Kyungsan jungang sijang. Medicinal plants extracted with 80% ethanol at boiling point for 3 hrs was used as antibacterial agent after freeze dried. This study was conducted to find antibacterial agent against growth of dental caries bacteria. St. mutans KDJ-50 from 32 medicinal plants of which safety was indetified. The result of using paper disc method. Caryophylli Flos. Coptidis Rhizoma. Phellodendri Cortex. Schizamdrae Fructs. Myristicae Semen, Crataegi Fructus and Acori Graminei Rhizoma was selected as antibacterial agent. The result of viable cell counting method. the antibacterial activity of Caryophylli Flos was highest among tested 7 medicinal plants followed by Phellodendri Cortex and Coptidis Rhizoma. The extinction effect of the St. mutans by Caryophylli Flos was shown with the addition of 0.5 (w/v) in the medium. The high antibacterial activity was acquired at high extraction temperature and long extraction temperature. The antibacterial activity of Caryophylli Flos was not effected by the concentration of ethanol.

Growth of ZnO:Al transparent conducting layer on polymer substrate for flexible film typed dye-sensitized solar cell

곽동주,Ji-Hoon Kim,박병욱,성열문,박민우,추영배 한국물리학회 2010 Current Applied Physics Vol.10 No.2

Aluminium-doped zinc oxide (ZnO:Al) conducting layer was deposited on polyethylene terephthalate (PET) substrate by r.f. magnetron sputtering to investigate the possible application of the film as transparent conducting electrode for film-typed dye-sensitized solar cells (FT-DSCs). The structural and electrical properties of ZnO:Al thin film were influenced significantly by the position of PET substrate and by also gas pressure. The minimum resistivity of 2.1 × 10-3 Ω cm was obtained at gas pressure of 5 mTorr. The deposition rate of ZnO:Al film at 5 mTorr of gas pressure was 248 nm/min. The efficiency of prepared FT-DSCs sample with ZnO:Al electrode showed about 2.1% (FF: 0.54, Voc: 0.73 V, Jsc: 5.3 mA/㎠).

구강균 Streptococcus sanguis에 대한 황백의 생육 저해 효과

곽동주,남상용,이덕수 대한치과기공학회 2002 대한치과기공학회지 Vol.24 No.1

To develop the natural antibacterial agents which don't have any toxicity against man, collected several speciesof medicinal plants were tested for their antibacterial activity from dental caries bacteria Streptococcus sanguis.The result of using paper disc method and the result of viable cell counting method, Phellodendri Cortex wasselected as antibacterial agent. The high antibacterial activity was acquired at high extraction temperature and longextraction temperature. The antibacterial of Phellodendri Cortex was not effected by the concentration of ethanol.

도재로를 이용한 납착 조인트의 인장 강도

곽동주 한국위생과학회 1996 한국위생과학회지 Vol.2 No.1

This study was under taken to compare the tensile strength of solder joints using a porcelain furnace using a gas-oxygen torch. Four metal ceramic alloy systems were used in making the specimens: gold-platinum-palladium, gold-palladium, palladium-silver and, nickel-chromium-beryllium. 120 Specimens were fabricated and assembled using an uniformed gap distance of 0.25mm. Fifteen specimens of each alloy were soldered using porcelain furnace. They were subjected to six simulated porcelain firing cycles and then to tensile loading until specimen failure occurred. Porcelain furnace soldering of gold-palladium and palladium-silver alloys produced post-solder joints that were as strong as those produced using gas-oxygen torch soldering. Porcelain furnace soldering of the Ni-Cr-Be alloy produced joints that were as strong as those produced using gas-oxygen torch soldering, but it was difficult to obtain consistently strong solder joints. Porcelain furnace soldering of the gold-platinum-palladium alloy produced significantly weaker joints than those produced using gas-oxygen torch soldering.

고성능 고분자 절연재료의 특성평가

곽동주 한국전기전자재료학회 1993 電氣電子材料學會誌 Vol.6 No.1

초전도 기기에 사용되는 고체 절연재료는 초전도 상태에서 상전도 상태로 천이시에 발생하는 임펄스 전압의 반복과전과 대전류에 의한 전자응력하에서 그 절연 성능이 충분히 발휘되어야 한다. 본 연구에서는 초전도 기기의 절연재료로 유력시되고 있는 결정성 PET에 임펄스 전압이 연속 과전될 때, 이 재료의 압축응력하에서의 절연강도특성에 미치는 연속과전의 효과를 검토하였다. 그 결과에 의하면 PET에 호모전하가 주입되면 임펄스 절연강도가 헤테로 전하주입시 보다 약 4MV/cm정도 높다. 한편, PET에 전하주입의 효과를 억제시킨 임펄스 진성절연강도는 압축응력의 증가와 함께 증가하여 최대치에 도달한 후 점차 감소하며 직류 절연강도 및 호모전하 주입시의 임펄스 절연강도보다 낮다.