재생 Al₂O₃분말을 이용한 Al₂O₃세라믹스의 소결 특성 연구

한상목,신대용 강원대학교 석재복합신소재제품연구센터 2001 석재연 논문집 Vol.6 No.-

Al2O3 세라믹스의 재활용을 위한 소결거동을 조사하기 위하여 재생 Al2O3 분말의 첨가량, 입자크기 및 소결온도에 따른 시편의 물리ㆍ기계적 특성을 측정하였다. 1,650℃에서 소결한 순수 Al2O3 시편을 급랭에 의하여 500㎛ 정도의 입자로 파쇄한 후, 자동유발을 이용하여 40㎛ 전ㆍ후로 분쇄하였다. 분쇄한 Al2O3 분말과 순수한 Al2O3 분말을 적정비로 혼합 후, 재소결에 의하여 제조한 Al2O3 세라믹스의 재생 Al2O3 분말의 첨가량, 입자 크기 및 소결온도에 따른 시편의 밀도 흡수율, 기공률, 3점곡강도 및 SEM 분석을 행하였다. 재생 Al2O3 분말의 첨가량이 증가함에 따라 시편 내에 존재한 기공에 의하여 밀도와 3점곡강도는 감소하였으나, 1,650℃에서 소결한 시편의 3점곡강도는 200 MPa 이상으로 구조용재료로 사용이 가능하였다. 또한, 재생 Al2O3 세라믹스 100wt%의 유리분말을 첨가하요 1,650℃에서 소결한 시편은 첨가한 유리분말의 고온용융에 의하여 생성한 액상에 의하여 물리ㆍ기계적 성질은 감소하였다. The sintering behavior of the Al2O3 composites for recycling Al2O3 powder was investigated as a function of the recycling Al2O3 powder and particle size with respect to physical and mechanical properties. Pure Al2O3 specimen was fabricated by sintering and was crushed into powder under 40㎛ in particle size by thermal shock treatment and automatic mortar crushing. Then, the crushed Al2O3 powder was mixed with pure Al2O3 powder, and the mixture was subjected to re-sintering to reuse Al2O3 composites. The reclaimed Al2O3 specimen were investigated by 3-point bending strength and SEM observation of microstructure. Density and 3-point bending strength of the reclaimed Al2O3 composites decreased as the addition amounts of recycled Al2O3 powder increased. The average 3-point bending strength of specimens heated at 1,650℃ were over 200 MPa. SEM observation indicated that pore distribution was inhomogeneous and pores were still resided in specimen, Pores, consequently, formed cracks which markedly decreased bending strength. Futhermore, 10wt% glass containing reused Al2O3 specimens were decreased physical and mechanical properties, so called over-sintering behavior.

A study on the solid-liquid 2 phase helical flow in an inclined annulus

한상목,김영주,우남섭,황영규 대한기계학회 2008 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.22 No.10

An investigation is conducted to understand hydraulic transport characteristics of a solid-liquid mixture flowing vertically upward. Namely, this is the instance that solid particles are carried by non-Newtonian fluids in a slim hole concentric annulus with rotating inner cylinder. In this study a clear acrylic pipe was used in order to observe the movement of solid particles. The bulk axial velocities varied from 0.4 m/s to 1.2 m/s. The mud systems which were utilized included aqueous solution of sodium carboxymethyl cellulose (0.2~0.4%CMC) and 5% bentonite solutions. Solid volumetric concentration and pressure drops were measured for the various parameters such as inclined annulus, flow rate, and rotational speed of inner cylinder. For both CMC and bentonite solutions, the higher the concentration of the solid particles are, the larger the pressure drops become.

지진가속도 계측 및 지진관측소 구축 타당성 연구

한상목,우남섭,하지호,김태우,이왕도,김기석,양재열,김영주 한국산업융합학회 2020 한국산업융합학회 논문집 Vol.23 No.3

Therefore, it was agreed that an earthquake monitoring station should be set up within the site of Handong University by analyzing drilling data and Disaster such as earthquakes is urgently needed to prepare for earthquakes in that people’s lives and national development depend on the nation’s ability to manage disasters. Many experts say that the Korean Peninsula is also under the influence of earthquakes and is not a safe zone for earthquakes. A seismological observatory will be established in Pohang to monitor ground sensors and study seismic characteristics through the task of “Development of Smart Sensor-based Intelligent Information Platform in Earthquake Region.” Therefore, it was agreed to set up a seismological observatory within the site of Handong University by analyzing drilling data and conducting on-site surveys in northern Pohang, which were heavily damaged by liquefaction and earthquakes. In this study, it was decided to make a comprehensive judgment by considering the geological characteristics of the site, whether it can perform functions, and the convenience of construction and maintenance for the final site of the seismological observatory discussed with Handong University. After completing a feasibility review on selecting a site for Handong University, we will establish a seismological observatory and actively utilize it for seismic research using data from alarm issuance and seismic data in the event of a future earthquake.

온라인 문의에 대한 효과적인 고객 응대 시스템 개발

한상목 한국전자거래학회 2002 한국전자거래학회 학술대회 발표집 Vol.2002 No.-

수질정화용 실리케이트 다공질 담체 제조

한상목,신대용 강원대학교 부설 석재복합신소재 제품연구센터 2000 석재연 논문집 Vol.5 No.-

석탄회와 벤토나이트 혼합시료의 열분석 결과, 다공질체를 제조하기 위하여는 석탄회와 벤토나이트에 흡착되어 있는 흡착수의 이탈과 유기물의 연소가 완료되는 900℃이상의 열처리가 필요하였다. 벤토나이트의 첨가량과 열처리 온도가 증가함에 따라 다공질체의 미세구조가 치밀화되어 부피비중과 압축강도는 증가하였으며 흡수율과 기공률은 감소하였다. 900℃에서 2시간 열처리한 9FAIB시편의 부피비중은 1.23g/㎤, 기공률 47.5%, 흡수율 37.3% 및 압축강도 10.1MPa의 값을 나타내었으나, 1,100℃에서 2시간 열처리한 5FA5B 시편의 부피비중은 1.59g/㎤ 기공률 6.5%, 흡수율 4.5% 및 압축강도 19.3MPa의 값을 나타내었다. 본 연구에서는 아미노산의 첨가량이 증가할수록 부피비중과 압축강도는 증가하였으며 흡수율과 기공률은 감소하였다. Utilization of fly-ash by-product from coal fired power plants and classified as general waster became very important problem to solve in the environmental protection and recycling of waste materials. To investigate the possibility of large scale substitution of fly-ash as a raw materials for porous sintered materials for water-purifier, it was prepared with fly-ash and bentonite at 900-1100℃, and their physical properties were established by XRD, SEM, bulk density, porosity, water absorption and compressive strength test. The bulk density and compressive strength of the sintered bodies heat-treated at 900℃ made from 90wt% of fly-ash and 10wt% of bentonite was about 1.23g/㎤ and 15MPa. From the water absorption and porosity analysis of the sintered materials, a decrease of porosity and water absorption were observed with increasing the bentonite content in raw materials, water absorption and porosity were 37.3% and 47.5%. Pore with diameter of about 10㎛ were produced in porous sintered materials. In this study, it was shown that the porous sintered materials have a good performance of water-purifier with many pores and an adequate strength.

Al_2TiO_5-점토 복합체를 이용한 원적외선방사재질의 개발

한상목,신대용 강원대학교 산업기술연구소 2000 産業技術硏究 Vol.20 No.A

Sintered Al_2TiO_5 has a very low thermal expansion and infrared radiative selectively emitting large amounts of far infrared rays. However, it is week in mechanical strength. Spectral infrared emittance, thermal expansion coefficient, and mechanical strength of Al_2TiO_5-clay composites were studied to develop a material for far infrared radiators. The composites containing 10∼50 mass% Jungsan clay had high emittance in the range of 2,000∼200cm-1. The bending strength of the Al_2TiO_5-clay composites increased with increasing clay content. The Al_2TiO_5-clay composites with a clay content of 50mass% and heat-treated at 1,200℃ had a large strength for infrared radiators ; 86MPa. The average linear thermal expansion coefficient from 200∼1,000℃ of the 50mass% Jungsan clay containing composited heat-treated at 1,200℃ was lower than 3.87X10-6/℃.

고속 신호 획득을 위한 SoC GPS수신기의 설계 및 구현

한상목,박찬식 충북대학교 컴퓨터정보통신 연구소 2004 컴퓨터정보통신연구 Vol.12 No.2

본 연구에서는 SOC을 목표로 GPS 수신기를 설계 및 구현 하였다. 5채널 GPS 수신기를 Altera사의 10만 게이트 Excalibur를 이용하여 구현할 수 있었다. 여기에 초기 신호 획득 시간을 줄이기 위해 다중 상관 방식을 추가하였다. 질제 측정치를 이용하여 실험한 결과는 이중 장관기일 경우 40% 그리고 사중 상관기일 경우 60% 이상 성능 향상됨을 보여주었다. 본연구의 결과는 차세대 GPS 수신기와 갈리레오 수신기설계 및 제작에 쉽게 적용할 수 있을 것이다. A design and implementation of SoC based GPS receiver is given in this paper. A 5 channels GPS receiver is implemented using Alteta's Excalibur with 100 thousand gates. A multiple correlation method is added to SoC based GPS receiver to reduce signal acquisition time. Experimental results show that improvement of more than 40% and 60% can be made by using dual-correlator and quad respectively. It is expected that these results can be easily applied into the design and implementation of GPS/Galileo receivers.

코디어라이트-Al_2TiO_5계 원적외선 방사체 제조

한상목,신대용 강원대학교 부설 석재복합신소재 제품연구센터 2000 석재연 논문집 Vol.5 No.-

Al_2TiO_5의 첨가량과 열처리 온도가 증가함에 따라 Al_2TiO_5상이 증가하였으며 Al_2TiO_5의 분해가 억제되었다. 1200℃의 열처리시 cordiertite와 Al_2TiO_5이외에 spinel과 mullite가 존재하였으며 1,250℃에서 spinel상은 감소하였으며 cordierite, Al_2TiO_5 및 mullite의 상이 증가하였다. 9CA 복합체는 1200℃에서 cordierit가 생성되었으며, 첨가량이 20wt%이상인 CA 복합체는 1300℃에서 cordierite가 생성되어 Al_2TiO_5의 첨가량이 증가함에 cordierite의 생성온도가 증가하였다. Cordierite 원료 조합물을 1,350℃로 열처리하였을 때 cordierite의 합성이 가능하였으며, Al_2TiO_5의 첨가량과 열처리 온도가 증가함에 따라 부피비중과 3점곡강도는 증가하였으나, 겉보기기공률과 흡수율은 감소하였다. 9CA 복합체를 1,200℃에서 열처리 하였을 때 부피비중 2.45 g/㎤, 겉보기기공률 0.25%, 흡수율 0.21% 및 155 MPa의 3점곡강도를 나타내어 coirdierite의 생성온도가 200℃ 감소되었다. Al_2TiO_5의 첨가량이 30wt%까지 복합체의 3점곡 강도는 증가하였으나, 첨가량이 30 wt%에서 40 wt%로 증가함에 따라 Al_2TiO_5의 열팽창계수의 이방성에 의한 미세균열이 발생하여 3점곡강도가 감소하였다. CA복합체는 Al_2TiO_5의 첨가량이 증가할수록 이력곡선의 면적과 평균열팽계수도 증가하였다. 1,200℃에서 3시간 열처리한 9CAC 복합체의 평균열팽창계수는 2.56×10^-6/℃, 1300℃에서 3시간 열처리한 7C3A 및 5C5A 복합체는 3.5210^-6/℃와 4.12×10^-6/℃를 나타내었다. Thermal properties of cordierite-Al_2TiO_5 composites of infrared radiator have been investigated as a function of Al_2TiO_5 additives(x=10~50 wt%). The emittance of composites containing 10% wt% Al_2TiO_5 heated at 1,200℃ for 3 hr, the emittance was about 0.3 and 0.92 in the ranges of 3,400~2,500 cm^-1 and 2,500~400cm^1, respectively. Compared with cordierite monolithics a substantial increase of sintering temperature range for composites was observed, which was due to the formation of cordierite and glass phase at relatively ow temperatures. The bulk density of the cordierite-Al_2TiO_5 composites increased with incresing Al_2TiO_5 content. The bending strength of composites showed its maximum at 30 wt% Al_2TiO_5 content, then decreased by a small amount at 40 wt% Al_2TiO_5 content. However, the microcracks formed was not serve enough to produce a significant decrease in strength, which was also evidenced by the continuous increase of thermal expansion coefficient up to 40 wt% Al_2TiO_5 content. 90 wt% cordierite-10 wt% Al_2TiO_5 composite heated at 1,200℃ had an adequate strength for infrared radiators; 155MPa. The degree of thermal expansion hysteresis increased with increasing Al_2TiO_5 content and the mean thermal expansion coefficient increased with increasing Al_2TiO_5 content. The thermal expansion coefficient of 90wt% cordierite-10 Al_2TiO_5 composite heated at 1,200℃ was 2.56×10^6/℃.

초보자를 위한 해설 -유리와 유약

한상목 이화여자대학교 도예연구소 1981 陶藝硏究 Vol.- No.3

침전법에 의한 CaCO₃:Sn^(2+) 형광체의 합성

한상목,신대용,윤봉구 강원대학교 부설 석재복합신소재 제품연구센터 2004 석재연 논문집 Vol.9 No.-

침전법을 이용하여 CaCO₃를 합성한 후, 활성제로서 Sn^(2+)를 도핑하여 CaCO₃:Sn^(2+) 형광체를 합성하고 결정상과 형상 및 Sn^(2+) 첨가량에 따른 형광특성을 조사하였다. CaCl₂·2H₂O-(NH₄)₂CO₃수용액에 NH₄OH를 첨가하여 pH가 증가하면 입자의 응집이 관찰되지 않고 vaterite상이 장시간 안정하게 존재하였으며 pH 11에서는 1~3㎛의 순수한 구형 vaterite상이 얻어졌다. Vaterite인 구형 CaCO₃:Sn^(2+) 형광체와 열처리한 구형의 calcite형 CaCO₃:Sn^(2+) 형광체는 230 nm에서 최대로 여기되어 465 nm에서 최대 발광강도를 나타내었다. 합성된 CaCO₃:Sn^(2+) 형광체는 결정상과 관계없이 SnCl₂·2H₂O의 첨가량이 2 mol%일 때 가장 강한 발광강도를 나타내었으며, 능면체의 calcite형 CaCO₃:Sn^(2+)형광체는 열처리하여 안정화된 구형의 calcite CaCO₃:Sn^(2+) 형광체와 구형의 vaterite형 CaCO₃:Sn^(2+) 형광체에 비해 높은 발광강도를 나타내었다. Vaterite type of CaCO₃ was synthesized by using the precipitation method(CaCl₂-(NH₄)₂CO₃ system) with addition of NH₄OH at different temperature, time, pH and concentration. As a result, pure vaterite having spherical shape(0.1~10 ㎛ in size) was formed at the condition of high pH(>11) and high concentration(>5 M). CaCO₃:Sn^(2+) phosphors(spherical vaterite) were synthesized at CaCl₂-SnCl₂-(NH₄)₂CO₃-NH₄OH system. CaCO₃:Sn^(2+) phosphors(spherical vaterite) were transformed to CaCO₃:Sn^(2+) phosphors(spherical calcite) by heating at 550℃ for 10 min. The Particle sizes of CaCO₃:Sn^(2+) phosphors(rhombohedral calcite) and CaCO₃:Sn^(2+) phosphors (spherical vaterite) were 10~15 ㎛ and 1~3 ㎛ respectively. The excitation spectrum of CaCO₃:Sn^(2+) phosphors(spherical vaterite and spherical calcite) exhibited a maximum peak intensity at 230 nm with a narrow absorption band from 220 nm to 240 nm. At the excitation spectrum of 275nm, the emission spectrum of CaCO₃:Sn^(2+) phosphor (rhombohedral calcite) with SnCl₂of 2 mol% exhibited a maximum peak intensity at 465 nm of bright blue fluorescence. Also, the emission spectrum of CaCO₃:Sn^(2+) phosphors(spherical vaterite, spherical calcite) exhibited a maximum peak intensity at 465 nm but exhibited weak peak intensity than CaCO₃:Sn^(2+) phosphors(rhombohedral calcite).