Controlled infiltration profile of SiC coating layer on graphite by Si vapor deposition reaction

Kuk-Jin Hwang,Si-Young Bae,Kyoung-Ho Kim,Yoon-Cheol Lee,Jung-Tae Hwang,Heesoo Lee,Seong Min Jeong,Myung-Hyun Lee 한양대학교 세라믹연구소 2019 Journal of Ceramic Processing Research Vol.20 No.2

SiC-coated graphite was successfully fabricated at different temperatures (1300-1600 oC) through a silicon vapor depositionreaction (Si-VDR) process. Si powder was used for the Si source of the SiC coating layers. When Si powder was evaporatedat high temperature near the melting point of bulk Si, Si gases are moved and changed into Si liquid at the surface of thegraphite. The high-temperature process facilitated the formation of SiC coating layers on the graphite. The microstructural,mechanical, and thermal oxidation properties of the coated graphite were investigated.

Formation of silicon nanoparticles by a pressure induced nucleation mechanism.

Kang, Myung-Koo,Kim, Si Joon,Kim, Hyun Jae RSC Pub 2013 Nanoscale Vol.5 No.8

<P>Formation of silicon nanoparticles (SiNPs) was achieved using excimer laser crystallization of an amorphous Si (a-Si) thin film using a SiO2 capping layer (C/L) with improved thin-film transistor (TFT) performance due to the enlarged grain size of polycrystalline Si (poly-Si). After laser irradiation of an a-Si thin film covered with C/L, fluctuation in the surface morphology of the C/L was observed above the critical laser energy density (Ecr) with the formation of SiNPs. The grain size of the poly-Si layer after crystallization increased abruptly at the same time. A non-uniform pressure distribution beneath the SiO2 C/L was proposed for the initiation of nucleation, which is named pressure induced nucleation (PIN) mechanism. Following nucleation, the release of latent heat made it difficult for the remnant liquid Si to solidify and the volume increased due to the density difference between the liquid and solid Si. Consequently, the pressure on the liquid Si caused SiNPs to sprout through the SiO2 C/L as grains grew from the low temperature to high temperature point. This study offers not only a simple method to fabricate SiNPs with controllable size/density but also larger grain size with lower laser energy density, which leads to higher TFT performance.</P>

The Change of Skeletal Muscle Mass Is Associated with Hepatic Steatosis in Non-Alcoholic Fatty Liver Disease

( Do Seon Song ),( U Im Chang ),( Seong Woo Go ),( Jeong Won Jang ),( Si Hyun Bae ),( Seung Kew Yoon ),( Jin Mo Yang ) 대한간학회 2018 춘·추계 학술대회 (KASL) Vol.2018 No.1

Aims: We aimed to investigate the association between the change of muscle mass and change of fibrosis and steatosis in NAFLD patients. Methods: We analyzed 2,893 NAFLD subjects who had health check-up more than twice in St. Vincent’s Hospital between November 2009 and December 2017. NAFLD was diagnosed by ultrasound, and appendicular muscle mass (ASM) was assessed by Inbody 720, and Sarcopenia index was calculated as ASM divided by weight (SI%) and ASM divided by body mass index (SI-BMI). Non-invasive markers were used to evaluate the severity of hepatic fibrosis and steatosis; NAFLD fibrosis score (NFS), Fibrosis-4 (Fib-4) score, and Forn’s index for fibrosis, and hepatic steatosis index (HSI) and fatty liver index (FLI) for steatosis. Results: The mean age was 47.3±10.4 years, and 1956 subjects (67.6%) were male. Diabetes, hypertension, metabolic syndrome were more prevalent in sarcopenic subjects (P<0.01), and non-invasive fibrosis and steatosis markers were higher in sarcopenic subjects (P< 0.01). The mean interval between two health check-up was 39.8±21.9 months. There was no significant association between the change of NFS, Fib-4, and Forn’s index and the change of SI% and SI-BMI (all P >0.1). However, the changes of HIS and FLI were significantly associated with the change of SI% and SI-BMI (all P<0.01). Multivariate logistic analysis demonstrated the independent association between the change of skeletal muscle mass and the changes of non-invasive steatosis markers after adjusting for other confounding factors (all P< 0.001). However, the changes of non-invasive fibrosis markers did not show an independent association with the change of appendicular muscle mass after adjusting for other confounders (all P >0.1) Conclusions: The change of muscle mass is strongly associated with the change of hepatic steatosis, but not the change of fibrosis.

석탄회분의 융착형성 연구

이시훈,박주식,임영준,김형택 한국화학공학회 1996 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.34 No.1

본 연구에서는 DTF를 이용하여 준역청탄인 Alaska탄의 회분과 deposit을 제조하고 조성을 분석하여 각각의 조성이 용융성에 미치는 영향을 고찰하였으며 ASTM 회분의 결과와 비교하였다. ASTM 회분은 alumina, silica, mullite, Ca-com-pound 등이 결정성으로 존재하는 반면 DTF 회분은 표면에 K, Fe, Ca 등이 농축된 구형의 drop이 만들어지는 것을 알 수 있었다. 또한 DTF 회분에는 mullite만이 결정성으로 존재하였다. Deposit은 용융후 고형화된 glass phase로 만들어 졌는데 Fe는 Fe^(3+) silicate로 전이되고 deposit하부에 Si가 농축되는 것으로부터 석탄 내의 무기물 조성 중에 용융을 지배하는 것은 Si인 것을 알 수 있었다. Alaska탄은 ASTM 회분분석결과로부터는 용융성이 강하게 예측되었으나 DTF에서 형성된 deposit 분석결과 표면에 부착강도를 낮게 하는 Ca가 농축되어 열전달면에서의 제거는 용이한 것으로 판단되었다. Ash and deposits were made using Alaska sub-bituminous coal in a drop tube furnace(DTF) and the effects of their compositions on fusion were compared with those of the ashes prepared from the ASTM aching procedure. It has been found that the ASTM ash includes alumina, silica, mullite, and Ca compounds as crystalline phases, whereas the DTF ash includes spherical drops with K, Fe, and Ca condensed on the surface. In a DTF ash, only mullite existed as crystalline phase. 'Che deposits existed as glass phases which were formed by solidification from melts, and Fe was transformed to Fe^(3+) silicate and Si was concentrated on the lower part of the deposit. This fact indicates that, among various inorganic elements in coal, Si controls the fusion. Although it was initially predicted that Alaska coal ash have strong slagging propensity based on the results of ASTM ash characterization, the results of analysis of the DTF deposits shows that the deposits can be easily removed from the heat transfer area because it is enriched with Ca which reduces the strength of its adhesion to the solid surface.

석면함유 슬레이트 지붕 물받이 퇴적물 중 석면 섬유 함유율

임지현,한솔민,김현석,신유민,박시은,허정윤,김민영,장봉기 순천향대학교 기초과학연구소 2022 순천향자연과학연구 논문집 Vol.28 No.1,2

This study attempted to determine the degree of asbestos release from the aging slate roof by comparing the asbestos content in the slate roof rain gutter with a colored steel plate (tin plate) over the slate roof. Four slate roof houses located in Haengmok-ri, Asan-si, Chungcheongnam-do, and one house constructed with a colored steel plate on the slate roof were selected to collect the sediment of the roof rain gutter. The asbestos fiber content was calculated by a point counting method using a polarization microscope after pretreatment with conversion treatment and hydrochloric acid treatment. The average asbestos content of the four slate roof rain gutter were 1.89%. However, asbestos was not detected in the Slate covering roof rain gutter, which were constructed on the slate roof. Asbestos fiber content was the highest at 2.89% in the slate roof rain gutter installed in 1976, followed by 2.44% in 1953. From the above results, it is necessary to minimize secondary damage as asbestos fibers released from slate roof houses to the surrounding atmosphere or leaked from slate roofs as rainwater may cause soil pollution and seriously affect residents' health. Although covering with colored steel plates (tin plates) has been shown to prevent the leakage of asbestos fibers to some extent, it is believed that a policy alternative to remove the slate roof as soon as possible is needed to solve the fundamental problem.

Novel Trials to Control Harmful Algal Blooms in Seawater

Hyun?Jae Shin,Hoon Cho,Un?Sun Jin,Yun?Kyung Park,Si Wouk Kim 한국생물공학회 2010 한국생물공학회 학술대회 Vol.2010 No.10

Effects of Phenytoin and Diazepam on the Seizure Activity in the Cortical Dysplasia Animal Models

Kim, Si-Hyung,Choi, In-Sun,Cho, Jin-Hwa,Park, Eun-Ju,Jang, Il-Sung,Choi, Byung-Ju,Kim, Hyun-Jung,Kim, Young-Jin,Nam, Soon-Hyeun The Korean Academy of Oral Biology 2006 International Journal of Oral Biology Vol.31 No.2

Dysplasia-associated seizure disorders are markedly resistant to pharmacological intervention. Relatively little research has been conducted studying the effects of antiepileptic drugs(AEDs) on seizure activity in a rat model of dysplasia. We have used rats exposed to methylazoxymethanol acetate(MAM) in utero, an animal model featuring nodular heterotopia, to investigate the effects of AEDs in the dysplastic brain. Pilocarpine was used to induce acute seizure in MAM-exposed and age-matched vehicle-injucted control animals. Field potential recordings were used to monitor amplitude and numbers population spikes, and paired pulse inhibition in response to stimulation of commissural pathway. Two commonly used AEDs were tested: diazepam 5, 2.5mg/kg;phenytoin 40, 60mg/kg. Diazepam(DZP) and phenytoin(PHT) reduced the amplitude of population spike in control and MAM-exposed rats. However, the amplitude of population spike was nearly eliminated in control rats as compared to the MAM-exposed rats. Pharmaco-resistance was tested by measuring seizure latencies in awake rats after pilocarpine administration(320mg/kg, i.p.) with and without pretreatment with AEDs. Pre-treatment with PHT 60 mg prolonged seizure latency in control rats, but not in MAM-exposed animals. The main findings of this study are that acute seizures initiated in MAM-exposed rats are relatively resistant to standard AEDs assessed in vivo. These data suggest that animal model with cortical dysplasia can be used to screen the effects of potential AEDs.

A Study on Improvement and Degradation of Si/SiO₂ Interface Property for Gate Oxide with TiN Metal Gate

Lee, Byung-Hyun,Kim, Yong-Il,Kim, Bong-Soo,Woo, Dong-Soo,Park, Yong-Jik,Park, Dong-Gun,Lee, Si-Hyung,Rho, Yong-Han The Korean Institute of Electrical and Electronic 2008 Transactions on Electrical and Electronic Material Vol.9 No.1

In this study, we investigated effects of hydrogen annealing (HA) and plasma nitridation (PN) applied in order to improve $Si/SiO_2$ interface characteristics of TiN metal gate. In result, HA and PN showed a positive effect decreasing number of interface state $(N_{it})$ respectively. After FN stress for verifying reliability, however, we identified rapid increase of $N_{it}$ for TiN gate with HA, which is attributed to hydrogen related to a change of $Si/SiO_2$ interface characteristic. In contrast to HA, PN showed an improved Nit and gate oxide leakage characteristic due to several possible effects, such as blocking of Chlorine (Cl) diffusion and prevention of thermal reaction between TiN and $SiO_2$.

폐암과 동반되어 나타난 기관기관지병증 골연골형성증 1예

이영진,전현수,박시형,김모세,김현주,이승헌,이영민,이현욱,이현경 仁濟大學校 白病院 2010 仁濟醫學 Vol.31 No.-

Tracheobronchopathia osteochondroplastica (TPO) is a rare benign disease of unknown etiology characterized by multiple cartilaginous or bony submucosal nodules, which project into the tracheobronchial lumen. Although some disorders were reported combined with TPO, these seemed to be considered casual. We report a case of TPO that combined with adenocarcinoma of lung. She was 50-year-old non smoking woman presented with chronic cough with right chest pain. Lung mass on right lower lobe was found on chest x-ray, so lung cancer was suspected. Multiple scattered whitish small elevations from trachea to bronchial trees were found on bronchoscopic exam. We mistook these lesions for metastases from lung cancer and biopsies of these lesions were done. Transbronchial biopsy for right lower lobe mass lesion was also done. But biopsies from trachea and bronchus revealed TPO rather than lung cancer. Transbronchial lung biopsy of right lower lobe mass was diagnosed adenocarcinoma of lung. So TPO combined with adenocarcinoma of lung was diagnosed.

광양만에서 춘계와 하계 영양염류 첨가가 식물플랑크톤군집의 성장에 미치는 영향

배시우,김동선,최현우,김영옥,문창호,백승호,Bae, Si Woo,Kim, Dongseon,choi, Hyun-Woo,Kim, Young Ok,Moon, Chang Ho,Baek, Seung Ho 한국해양학회 2014 바다 Vol.19 No.1

춘계와 하계 광양만에서 식물플랑크톤 군집구조와 그들의 성장에 영향을 미치는 영양염제한 특성을 파악하기 위해서 만내외측의 20개 정점에서 생물학적 요인과 무생물학적 요인을 조사했다. 또한 식물플랑크톤 군집에 대한 영양염 첨가 효과를 알아보기 위해서 실험실에서 현장 20개 정점의 표층수를 이용하여 생물검정실험을 수행하였다. 전체 식물플랑크톤 군집의 90%이상을 규조류가 차지하였다. 이들 규조류중 Eucampia zodiacus와 Skeletonema costatum-like 종이 춘계와 하계에 각각 우점하였다. E. zodiacus와 S. costatum-like 규조류의 개체군 밀도가 춘계와 하계에 높은 밀도를 유지하게 된 이유를 간단히 설명하면, E. zodiacus 의 성장은 춘계 투명도가 높게 나타나 유광층내 광량의 증가가 원인으로 생각된다. 즉 유광층내 광량의 증가는 E. zodiacus의 개체수를 폭발적으로 증가시킬 수 있는 방아쇠 역할을 한 것으로 판단된다. 하계에 S. costatum-like이 전해역에서 우점한 이유는, 섬진강 담수 유입에 의한 낮은 염분과 함께 공급된 다량의 영양염은 그들 생물의 증식에 중요한 bottom-up 효과를 보였다고 판단된다. 실험실의 생물검정실험에서는 비록 내만(정점 8)과 외해(정점 20)에서 식물플랑크톤 군집의 최대 성장율은 유사하였지만, 인산염에 대한 반포화계수($K_s$)는 내만정점보다 약간 낮았다. 상대적으로 낮은 영양염농도에 적응한 세포는 낮은 인산염농도에서 충분히 성장할 수 있고, 다른 미세조류에 비하여 낮은 영양염농도의 조건에서 경쟁의 우위를 차지 할 것이다. 특히, 하계의 N영양염 첨가군의 효율은 대조군과 P영양염 첨가군에 비해서 높았다. 이는 광양만에서 하계에 N영양염의 공급이 섬진강을 통하여 계속적으로 유입되지만, 빠른 식물플랑크톤의 증식으로 인하여 N영양염 제한이 일어날 수 있다는 것을 시사할 수 있다. 반면, 규산염은 식물플랑크톤의 성장에 영향을 미치는 제한인자로 나타나지 않았고, 규조류의 분해로 인하여 Si의 재순환과 담수로부터 공급된 높은 규산염농도는 광양만에서 규조류 생태계를 유지할수 있는 유리한 조건이라 생각된다. In order to estimate the effect of nutrients addition for phytoplankton growth and community compositons in spring and summer season, we investigated the abiotic and biotic factors of surface and bottom waters at 20 stations of inner and offshore areas in Gwangyang Bay, Korea. Nutrient additional experiments were also conducted to identify any additional nutrient effects on phytoplankton assemblage using the surface water for the assay. Bacillariophyceae occupied more than 90% of total phytoplankton assembleges. Of these, diatom Eucampia zodiacus and Skeletonema costatum-like species was mainly dominated in spring and summer, respectively. Here, we can offer the season why the two diatom population densities were maintained at high levels in both seasons. First, light transparency of spring season in the euphotic zone was greatly improved in the bay. This improvement is one of important factor as tigger of increase in E. zodiacus population. Second, low salinity and high nutrient sources supplied by Seomjin River discharge are a main cue for strong bottom-up effects on S. costatum-like species during the summer rainy season. Based on the algal bio-assays, although maximum growth rate of phytoplankton communities at inner bay (St.8) were similar to those of outer bay (St.20), half-saturation constant ($K_s$) for phosphate at outer bay was slightly lower than those of inner bay. This implied that adapted cells in low nutrient condition of outer bay may have enough grown even the low phosphate and they also have a competitive advantage against other algal species under low nutrient condition. In particular, efficiency of N (+) addition in summer season was higher compared to control and P added experiments. In the bay, silicon was not a major limiting factor for phytoplankton growth, whereas nitrogen (N) was considered as a limiting factor during spring and summer. Therefore, a sufficient silicate supply form water mixing Si recycled from diatom decomposition and river water is favorable form maintaining diatom ecosystems in Gwangyang Bay.