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알루미나-아연붕규산염 유리를 이용한 저온 소결 다공성 세라믹스의 제조 및 특성
김관수,송기영,박상엽,김신,김성진,윤상옥,Kim, Kwan-Soo,Song, Ki-Young,Park, Sang-Yeup,Kim, Shin,Kim, Sung-Jin,Yoon, Sang-Ok 한국세라믹학회 2009 한국세라믹학회지 Vol.46 No.6
The low-temperature preparation of porous ceramics was carried out using mixtures of alumina-zinc borosilicate (ZBS) glass. The compositions of alumina-ZBS glass mixture with PMMA pore-former were unfortunately densified. Because PMMA was evaporated below the softening point of ZBS glass ($588{^{\circ}C}$), the densification through the pore-filling caused by the capillary force might occur. Howerver, those with carbon possessed pores where carbon was evaporated above the softening point. The porous ceramic having 35% porosity was successively fabricated by the low-temperature sintering process below $900{^{\circ}C}$ using 45 vol% of alumina, 45 vol% ZBS of glass, and 10 vol% of carbon as starting materials.
LTCC 기판재료 응용을 위한 다양한 충전제 함유 CaO-Al<sub>2</sub>O<sub>3</sub>-SiO<sub>2</sub> 유리복합체 연구
김관수,장호순,신현호,김인태,김신,한용현,윤상옥,Kim, Kwan-Soo,Jang, Ho-Soon,Shin, Hyun-Ho,Kim, In-Tae,Kim, Shin,Han, Yong-Hyun,Yoon, Sang-Ok 한국세라믹학회 2009 한국세라믹학회지 Vol.46 No.3
Influences of ceramic filler types and dose on the sintering, phase evolution, and dielectric properties of ceramic/CaO-$Al_2O_3-SiO_2$ glass composites were investigated. All of the specimens were sintered at $900^{\circ}C$ for 2 h, which conditions are required by the lowtemperature co-firing ceramic (LTCC) technology. Ceramic fillers of $Al_2O_3,\;SiO_2$, kaolin, and wollastonite were used. The addition of $Al_2O_3$ filler yielded the crystalline phases of alumina and wollastonite, and the densification over 95% of the relative density was achieved up to 50 wt% addition of the filler. For the cases of the fillers of $SiO_2$, kaolin, and wollastonite, crystalline phases of quartz, mullite, and wollastonite formed, while the densification decreased monotonically with the filler addition. In overall, all the investigated fillers with 10 wt% addition resulted in a reasonable sintering (over 95 %) and low dielectric constants (less than 6), demonstrating the feasibility of the investigated composites for application to a LTCC substrate material with a low dielectric constant.
김관수,윤상옥,심상흥,박종국,Kim, Kwan-Soo,Yoon, Sang-Ok,Shim, Sang-Heung,Park, Jong-Guk 한국전기전자재료학회 2007 전기전자재료학회논문지 Vol.20 No.1
The effects of $B_2O_3-SiO_2-R(R;CaO,\;BaO,\;ZnO,\;Bi_2O_3)$ borosilicate glass system on the sintering behavior and microwave dielectric properties of ceramic/glass composites were investigated as functions of modifier, glass addition ($30{\sim}50\;vol%$) and sintering temperature ($500{\sim}900^{\circ}C$ for 2 hrs). The addition of 50 and 45 vol% glass ensured successful sintering below $900^{\circ}C$. Sintering characteristics of the composites were well described in terms of modifier. Borosilicate glass enhanced the reaction with $Al_{2}O_{3}$ to form pores, second phases and liquid phases, which was responsible to component of modifier. Dielectric constant (${\varepsilon}_{r},\;Q{\times}f_{o}$) and temperature coefficient of resonant frequency (${\tau}_{f}$) of the composite with 50 and 45 vol% glass contents($B_{2}O_{3}:SiO_{2}:R=25:10:65$) demonstrated A-CaBS(7.8, 2,560 GHz, -81ppm/$^{\circ}C$), A-BaBs(5.8, 3.130 GHz, -64 ppm/$^{\circ}C$), A-ZnBS(5.7, 17,800 GHz, -21 ppm/$^{\circ}C$), A-BiBs(45 vol% glass in total)(8.3, 2,700 GHz, -45 ppm/$^{\circ}C$) which is applicable to substrate requiring an low dielectric properties.
김관수,최철영,장혜란,Kwan Soo Kim,M,D,Chul Young Choi,M,D,Hae Ran Chang,M,D 대한안과학회 2008 대한안과학회지 Vol.49 No.12
Purpose: A number of patients with accommodative esotropia who were initially well controlled with their optical correction will deteriorate. This study aims to examine the cautious clinical features of patients with accommodative esotropia during follow-up period by obtaining the prevalence and the predictive factors of deterioration in accommodative esotropia. Methods: The records of 89 patients with accommodative esotropia whose eyes were aligned with optical correction (including bifocals) to 8 prism diopters (PD) of esotropia or less were reviewed. All patients were followed for a period of at least 2 years. The patients whose alignment was increased to 10PD of esotropia or greater during the follow-up period were included into the deteriorated group. We obtained the rate of deterioration and compared the clinical features of the deteriorated and controlled group. Results: The mean follow-up period was 64.1±29.3 months. Seven (7.8%) of 89 patients was deteriorated. The mean interval of deterioration after initial optical correction was 41.8±26.9 months. The stereopsis was significantly worse in the deteriorated group p=0.024). The frequency of high AC/A ratio was also significantly higher in the deteriorated group (p=0.003). Conclusions: This study indicates that accommodative esotropia with high AC/A ratio or worse sensory status has an increased likelihood of deterioration.
213-nm Solid-State Laser 굴절교정각막절제술 시 각막표면 수분의 영향
김관수,최철영,차흥원,Kwan Soo Kim,Chul Young Choi,Hungwon Tchah 대한안과학회 2008 대한안과학회지 Vol.49 No.11
Purpose: To investigate the effect of surface fluid on the ablation rate and efficacy of 213-nm solid-state laser during photorefractive keratectomy (PRK). Methods: Twelve rabbits (24 eyes) underwent myopic PRK for the correction of 10 diopters using 213-nm solid-state laser. Photoablation was performed with removal of corneal surface fluid using the Weckcel® sponge every 5 seconds in one eye and without removal of corneal surface fluid in the control eye. The mean central corneal thickness (CCT) was evaluated preoperatively, and at 1 week, 4 weeks postoperatively. Results: The mean CCT of group 1 (with removal of corneal surface fluid) were 361.3±13.9 μm preoperatively and 321.4±18.5 μm at 4 weeks postoperatively. The mean CCT of group 2 (without removal of surface fluid) were 358.7±8.9 μm preoperatively and 338.4±12.0 μm at 4 weeks postoperatively. The mean ablation depths were 39.8±7.4 μm in group 1 and 20.3±5.8 μm in group 2 at 4 weeks postoperatively (p<0.05). Conclusions: Induced corneal surface fluid during PRK may influence the ablation efficacy and accuracy of solid-state laser. This result should be considered in clinical trialswith 213-nm solid-state laser, especially in high myopes. J Korean Ophthalmol Soc 2008;49(11):1723-1728
충북 증평 지질학습장 시험부지에 대한 물리탐사 및 지질공학 자료의 해석
김관수 ( Kwan-soo Kim ),윤현석 ( Hyun-seok Yun ),사진현 ( Jin-hyeon Sa ),서용석 ( Yong-seok Seo ),김지수 ( Ji-soo Kim ) 대한지질공학회 2016 지질공학 Vol.26 No.3
지하 매질의 물리적인 성질을 정확히 평가하기 위한 가장 일반적인 방법은 해당 지점에서 시추하여 채취한 암편을 대상으로 해석한 지질공학적인 실내시험 결과와 시추공 안에 삽입한 탐사 기구를 통해 얻은 지구물리학적인 자료를 함께 복합적으로 해석하는 것이다. 이 연구에서는 충북 증평의 지질학습장으로 예정된 시험부지 중의 한 곳에서 시추공 탐사 대신 수집한 지표 탄성파탐사(굴절법 및 표면파법) 자료로부터 얻은 P파 및 S파 속도구조와 이를 토대로 작성된 포아송 비 단면을 통해 노두에 좁은 폭으로 드러난 암석 환경(적색퇴적암, 회색화산암, 풍화 화산암) 및 접촉선에서 관찰된 단열, 파쇄대가 확인되는지 알아보았다. 또한 탐사 지역에 주로 분포하는 회색 화산암과 적색 퇴적암을 대상으로 지표지질 조사와 실내 지질공학 실험을 수행하였다. 탐사자료에서 평가된 동적 탄성계수 영률은 지질공학 자료의 정적 탄성계수보다 높았다. 실내 시험에서 회색화산암에 비해 공극률이 작고 함수비가 작은 것으로 평가된 적색퇴적암은 추가적으로 건기와 우기에 실시한 전기탐사(비저항 및 자연전위) 결과에서 건우기와 관계없이 상대적으로 전기비저항이 높고 그 변화 폭이 매우 작은 영역으로 확인되었다. 특히 높은 함수비와 공극률을 갖는 풍화된 회색 화산암과 함께 접촉선에서 좁게 발달한 단열 파쇄대가 우기 때의 충전율을 높이는 열린 통로의 역할을 한 것으로 해석된다. The best way of investigating the physical and mechanical properties of subsurface materials is the combined interpretation of data from borehole geophysical surveys and geotechnical experiments with rock samples. In this study two surface seismic surveys with refraction and surface-wave method are alternatively conducted for downhole seismic surveys in test site for geological field trip in Jeungpyung, Chungbuk. P- and S-wave velocity structures are delineated by refraction and MASW (multichannel analysis of shear waves) methods, respectively. Possion’s ratio section, reconstructed from P- and S-wave velocities, is correlated to the outcrop geological features consisting of reddish sedimentary rock, gray volcanic rock, and joints/fractures. In addition, rock samples representative for reddish sedimentary and gray volcanic features are geotechnically analyzed to provide physical, mechanical properties, and elastic modulus. Dynamic elastic moduli estimated from geophysical data is found to be higher than the one from geotechnical data. Reddish sedimentary rock characterized with low porosity and moisture content corresponds to the zone of low electrical resistivities and their small variations in the resistivity sections between the rainy and dry days. This trend suggests that the weathered gray volcanic rock and the nearby fractures with higher low porosity and moisture content are interpreted to be good carrier especially in rainy season.
식량 및 에너지자급률의 참조국가별 상호연관성 및 이행경로 분석
김관수 ( Kwan Soo Kim ),안동환 ( Dong Hwan An ),김윤진 ( Yun Jin Kim ) 한국농업경제학회 2014 農業經濟硏究 Vol.55 No.2
In this paper, we present results of an empirical investigation on correlation and transition path of food and energy self-sufficiency by reference group of countries (e.g., OECD, OPEC, HDI developed countries, HDI developing countries, transition countries). The results suggest the importance of controlling country specific effects self-sufficiency, our study found that correlation between them varies across reference groups. A catch-up story of HDI developing countries and transition countries is identified when the ``level`` of food and energy security is concerned. However, the same is found to be not true for the ``rate`` of food and energy security. This suggests that synergy effects between food and energy security is not fully utilized during the sample period.