인공치아용 수산화 인산칼슘 요업체의 제조

하조웅,정형진 한국세라믹학회 1983 한국세라믹학회지 Vol.20 No.1

the preliminary work on the prepartion of fine hydroxyapatite powder and the synthesis of dense hydroxyapatite ceramic from the powder were investigated for the development of artificial bone and tooth materials for implants. The effects of the process variables such as compositions of the raw materials the initial pH of the solutions and sintering temperature on the physical properties were investigated in order to determine the optimum conditions for the fabrication of tooth implant material. As the initial pH of the solutions was increased in the range of 10-11.6 the initial particle size of precipitates was decreased thus the sinterability of precipitates was improved. It was found that the composition of calcium rich of 1.75 in Ca/P mole ratio exhibited better sinterability and mechanical strength of the apatite ceramics for example the highest value of Vicker's hardness obtained from the compositions of 1.75 in Ca/P mole ratio was 764±30 Kg/mm2 compared to the maximum value of 600 kg/mm2 obtained from the compositions of 1.67 in Ca/P mole ratio.

入工歯牙用 水酸化 鱗酸칼슘 熏業体의 製造

하조웅(Jo-Woong Ha),정형진(Hyung-Jin Jung) 대한치과이식임플란트학회 1982 The Korean Academy of Implant Dentistry Vol.3 No.1

The preliminary work on the prepartion of fine hydroxyapatite powder and the synthesis of dence hydroxyapatite ceramic from the powder were investigated for the development of artificial bone and tooth materials for implants. The effects of the process variables, such as compositions of the raw materials, the initial pH of the solutions,and sintering temperature on the physical properties were investigated in order to determine the optimum conditions for the fabrication of tooth implant material. As the initial pH of the solutions was increased in the range of 10-11.6, the initial particle size of precipitates was decreased, thus the sinterability of precipitates was improved. It was found that the composition of calcium rich of 1.75 in Ca/p mole ratio exhibited better sinterability and mechanical strength of the apatite ceramics, for example the highest value of Vicker’s hardness obtained from the compositions of 1.75 in Ca/P mole ratio was 764 ± 30 Kg/mm2,compared to the maximum value of 600 Kg/mm2 obtained from the compositions of 1.67 in Ca/P mole ratio.

연구논문 - 에너지 , 환경분과 : Pb - ZSM -5 촉매상에서 ZSM -5 의 산도변화에 따른 메탄의 완전연소반응 고찰

김조웅,하재목,엄기태,박진우,함현식 한국공업화학회 1997 한국공업화학회 연구논문 초록집 Vol.1994 No.1

저온 상압하에서 ZSM -5 의 결정화 반응

김화중,이명철,김조웅,하재목 ( Wha Jung Kim,Myung Churl Lee,Jo Woong Kim,Jae Mok Ha ) 한국공업화학회 1997 공업화학 Vol.8 No.2

환류장치를 이용하여 저온-상압하에서 ZSM-5의 결정화 반응을 수행하였다. 반응에 사용된 물조성은 7.83Na₂O-0.25Al₂O₃-100SiO(₂-x)TPAB(r-y)H₂O로써 x는 1 몰 및 3몰, y는 3000몰, 3500 몰, 및 4000 몰이었다. 또한 저온-상압하에서 수행한 반응속도 연구를 통하여 얻어진 기초 자료를 토대로 Na₂O, TPABr 및 H₂O를 주요 인자로 한 2³ factorial 실험을 수행한 결과 물의 농도가 가장 중요한 인자임을 알 수 있었다. 생성된 결정은 형태가 매우 균일하고 잘 발달된 결정임을 알 수 있었고 BET 표면적은 평균 410m²/g에 이르는 것을 알 수 있었다. ZSM-5 was crystallized at low temperature and atmospheric pressure using reflux unit. The overall molar composition used in this study was 7.83Na₂O-0.25Al₂O₃-100SiO(₂-x)TPAB(r-y)H₂O where x is 1 and 3 mol, and y is 3000 mol, 3500 mol, and 4000 mol. 2³ factorial experiments were performed with the results of kinetics studies, showing Na₂O, TPABr, and H₂O as main factors. The result suggested that the concentration of H₂0 is the most important. The morphology of final product was very uniform showing well-defined crystals with BET surface area of ca. 410 m²/g.

RBSC/Graphite 복합재료의 기계적 특성에 관한 연구

서기식,박상환,하조웅,정윤중 한국세라믹학회 1998 한국세라믹학회지 Vol.35 No.6

안와 주변 방사선 치료 시 수정체 피폭선량 감소를 위한 2차 차폐의 유용성 평가

곽용국,홍순기,하민용,박장필,유숙현,조웅,Kwak, Yong Kuk,Hong, Sun Gi,Ha, Min Yong,Park, Jang Pil,Yoo, Sook Hyun,Cho, Woong 대한방사선치료학회 2015 대한방사선치료학회지 Vol.27 No.1

목 적 : 안와 주변 방사선 치료 시 수정체 피폭선량감소를 위하여 사용된 2차 차폐 block의 유용성을 알아보고자 한다. 대상 및 방법 : Human phantom(Alderson Rando Phantom, The Phantom Laboratory, USA)을 사용하여 CT(Somatom Definition AS, Siemens, Germany) 모의촬영 후 전산화치료계획시스템(Pinnacle, PHILIPS, USA)을 통해 실제 치료와 유사한 IMRT치료계획을 실시하였다. 2차 차폐를 위하여 두께 3mm 지름 25 mm의 납판과 3 mm tungsten eye-shield block(Extra small size, Radiation Products Design, Inc, USA)를 사용하였으며, TPS(Treatment Planning System) 상의 lens dose와 모의치료 상의 lens dose를 OSLD로 측정 비교하였다. 또한, 5 cm 두께의 acrylic phantom에 동일한 조건의 2차 차폐물인 3 mm 납판과 tungsten eye-shield block을 사용하여 200 MU(6 MV, SPD(Source to Phantom Distance)=100 cm, $F{\cdot}S\;5{\times}5cm$)를 조사 및 측정하였으며, 조사야 밖의 누설선 및 투과방사선 영향을 제한시키고자 8 cm 납블럭(O.S.B: Outside Scatter Block)을 적용하여 위와 동일한 실험을 시행하였다. 조사야로부터 1 cm 이격하여 phantom 끝 옆면에 OSLD(Optically Stimulated Luminescence Dosimeter)를 부착하였고, eyelid의 두께에 해당하는 bolus 3 mm를 적용하였다. 결 과 : human phantom을 이용하여 IMRT 치료계획 상의 Lens dose와 실 측정치는 각각 315.9, 216.7 cGy가 측정되었고, 3 mm 납판과 tungsten eye-shield block으로 2차 차폐 후 각각 234.3, 224.1 cGy가 측정되었다. acrylic phantom을 이용한 실험 결과는 no block, 3 mm 납판, tungsten eye-shield block을 사용했을 때 5.24, 5.42, 5.39 cGy가 측정되었으며, 조사야 밖에 O.S.B를 적용하여 no block, 3 mm 납판, tungsten eye-shield block을 실험한 결과 각각 1.79, 2.00, 2.02 cGy가 측정되었다. 결 론 : 광자선 조사 시 critical organ을 보호하기 위하여 2차 차폐를 적용할 시에는 field 외부일지라도 헤드 누설방사선 및 collimator & MLC 투과방사선이 존재하므로 치료부위와 beam 방향에 따라 금속과 같은 높은 원자번호의 차폐물질이 critical organ근처에 있다면 선량 증가의 원인이 될 수 있다는 사실을 알 수 있었다. 따라서 피폭선량 감소를 위한 2차 차폐의 시도는 분명 의미가 있었으나 미 검증된 시도는 오히려 역효과를 가져올 수 있다는 사실을 인지하여 QA를 통해 목적에 부합하는 결과가 나오는지를 사전에 알아보아야 할 것이다. Purpose : This study presents the usefulness assessment of secondary shield for the lens exposure dose reduction during radiation treatment of peripheral orbit. Materials and Methods : We accomplished IMRT treatment plan similar with a real one through the computed treatment planning system after CT simulation using human phantom. For the secondary shield, we used Pb plate (thickness 3mm, diameter 25mm) and 3 mm tungsten eye-shield block. And we compared lens dose using OSLD between on TPS and on simulation. Also, we irradiated 200 MU(6 MV, SPD(Source to Phantom Distance)=100 cm, $F{\cdot}S\;5{\times}5cm$) on a 5cm acrylic phantom using the secondary shielding material of same condition, 3mm Pb and tungsten eye-shield block. And we carried out the same experiment using 8cm Pb block to limit effect of leakage & transmitted radiation out of irradiation field. We attached OSLD with a 1cm away from the field at the side of phantom and applied a 3mm bolus equivalent to the thickness of eyelid. Results : Using human phantom, the Lens dose on IMRT treatment plan is 315.9cGy and the real measurement value is 216.7cGy. And after secondary shield using 3mm Pb plate and tungsten eye-shield block, each lens dose is 234.3, 224.1 cGy. The result of a experiment using acrylic phantom, each value is 5.24, 5.42 and 5.39 cGy in case of no block, 3mm Pb plate and tungsten eye-shield block. Applying O.S.B out of the field, each value is 1.79, 2.00 and 2.02 cGy in case of no block, 3mm Pb plate and tungsten eye-shield block. Conclusion : When secondary shielding material is used to protect critical organ while irradiating photon, high atomic number material (like metal) that is near by critical organ can be cause of dose increase according to treatment region and beam direction because head leakage and collimator & MLC transmitted radiation are exist even if it's out of the field. The attempt of secondary shield for the decrease of exposure dose was meaningful, but untested attempt can have a reverse effect. So, a preliminary inspection through Q.A must be necessary.

R.F. Magnetron Sputtering법을 이용한 ITO 박막 오존 가스센서의 제조 및 특성

권정범,정경근,이동수,하조웅,유광수,Kwon, Jung-Bum,Jung, Kyoung-Keun,Lee, Dong-Su,Ha, Jo-Woong,Yoo, Kwang-Soo 한국세라믹학회 2002 한국세라믹학회지 Vol.39 No.9

As an ozone gas sensor, the semiconductor gas sensor which is cheap, portable and simple in use and has a high sensitivity and an excellent selectivity, has been known as an alternative. In the present study, ITO ($In_2O_3 95%,\;SnO_2$ 5%) thin films were deposited on the alumina substrate by using R.F. magnetron sputtering method. The substrate temperature was 300$^{\circ}C$ and 500$^{\circ}C$, respectively and then some specimens were annealed at 500$^{\circ}C$ for 4h in air. ITO gas-sensing films formed crystallines before and after annealing. As results of gas sensitivity measurements to an ozone gas, the sensor deposited at 300$^{\circ}C$ and then annealed has the highest sensitivity (sensible below 1 ppm). As the operating temperature increased gradually, the sensitivity decreased but the response time and stability improved. 오존 가스센서는 저가이고 휴대 및 사용이 간편하며 감도가 높고 우수한 선택성을 지닌 반도체식 가스센서가 대안으로 부각되고 있다. 본 연구에서는 R.F. magnetron sputtering법을 이용하여 ITO($In_2O_3 95%,\;SnO_2$ 5%) 박막을 알루미나 기판위에 증착시켰다. 증착시 기판온도는 300$^{\circ}C$와 500$^{\circ}C$였고, 시편의 일부를 공기중 500$^{\circ}C$에서 4시간 동안 열처리하였다. ITO 가스 감지막은 열처리 전${\cdot}$후 모두 결정을 형성하였다. 오존 가스에 대한 감도측정 결과, 300$^{\circ}C$에서 증착한 다음 열처리한 센서에서 가장 높은 감도(1 ppm이하 감지 가능)를 나타내었다. 작동온도가 높을수록 감도는 줄어들었지만 빠른 응답 특성과 안정성을 가졌다.

저압 화학증착법에 의한 대면적 SiC 후막의 증착

김원주,박지연,김정일,홍계원,하조웅 한국세라믹학회 2001 한국세라믹학회지 Vol.38 No.5

일반 산업 및 원자력 관련 산업용 구조소재의 표면특성 향상을 위해 저압 화학기상 증착법에 의해 15~25cm 직경의 흑연기판 위에 고순도의 치밀한 SiC 증착층을 제조하였다. 미세구조와 두께가 균일한 증착층을 얻기 위하여 증착온도의 균일성, 반응가스 고갈효과, 가스 흐름 형태 등의 영향을 고려하였다. 이중에서 반응 용기내의 가스 흐름 형태가 증착층의 균일도에 가장 큰 영향을 주는 것으로 판단되었으며 가스 주입구의 위치와 크기를 조정함으로써 25cm의 직경을 갖는 흑연 기판에 두께 편차가 $\pm$12% 이내인 SiC 증착막을 제조할 수 있었다.

Electromechanical Properties of Pb(Zr, Ti)O$_3$ Films for MEMS Applications

김승현,Chang Young Koo,황철성,이동수,양정승,하조웅,Jung-Hoon Yeom,Kyu-Ho Hwang 한국물리학회 2003 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.42 No.IV

A systematic investigation of the piezoelectric and ferroelectric properties of PZT lms prepared by chemical solution deposition is performed for tetragonal (Zr/Ti = 30/70), morphotropic (52/48), and rhombohedral (70/30) composition. An atomic force microscope (AFM) is used to measure the magnitude of the eective longitudinal piezoelectric coecient (d33) of these lms. All lms are consistently highly textured (111) orientation and have dense microstructures. Slightly less degree of texture in higher Zr-rich composition is observed due to the lattice mismatch between PZT and Pt bottom electrode and higher activation energy for nucleation. Squareness of polarization hysteresis loops is optimized in tetragonal composition, which indicates the tetragonal PZT is closer to the ideal hysteresis behavior than other composition. It is shown that the piezoelectric coecient is dependent on the dielectric constant. The morphotropic PZT lms with 1 m thickness show the largest piezoelectric coecient values, which are comparable with those of bulk materials.

Scaling Issues of Pb(Zr, Ti)O$_3$ Capacitor Stack for High Density FeRAM Devices

김승현,Chang Young Koo,황철성,이동수,Dong-Yeon Park,Jieun Lim,하조웅,Jung-Hoon Yeom 한국물리학회 2003 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.42 No.IV

For realization of 32 Mb high density FRAM devices, the low stack height of capacitor from 750 nm to 300 nm should be accomplished with the scaling of thickness of PZT thin lms and electrodes below 100 nm. Otherwise, it is not possible of each capacitor to retain sucient distance with adjacent capacitors due to the diculty in obtaining steep etching slope of the capacitor, and which induces a critical device failure. To address these issues we explore the ferroelectric performance of the thickness scaled PZT thin lms (35 70 nm) on ultra thin bottom Pt electrodes (30 nm). It is observed that the switching performance of the thickness scaled PZT thin lms on sub-50 nm thick Pt bottom electrodes showed 1 V operation with sharp and rectangular hysteresis loops and high remanent polarization values (30 35 C/cm2), implying the possibility to realize 32 Mb FRAM devices and beyond. For a long-term stability of the capacitors, the lm thicknessdependent imprinting behavior was evaluated by a thermal stress process under a remanence bias. It is found that the voltage shift, which was attributed to the accumulation of charged defects near the electrode interface, increased linearly with increasing the lm thickness.