Coating with boron nitride on SiC fiber using atomic substitution

Woo‑Seong Tak,Jin‑Uk Hwang,Young‑Keun Jeong,Woo‑Sik Kim 한국세라믹학회 2020 한국세라믹학회지 Vol.57 No.2

To increase the mechanical properties of ceramic matrix composite, it is important that formation of lubricant layer for crack deflection between matrix and fiber. Therefore, we fabricated uniform boron nitride (BN) lubricant layer using atomic substitution method. Silicon carbide (SiC) fiber surface was modified with amine groups using (3-amonipropyl)triethoxysilane to coat SiC fiber with BN as a solid lubricant. Then, surface was coated with graphene oxide (GO). Boric acid powder was supplied to the GO-coated fibers and the samples were heat-treated at 1200–1400 ℃ under N2 and NH3 atmospheres. An uniform BN layer could be coated on SiC fiber with 10 nm-1.11 μm. Crystallinity and thickness of BN layer could be controlled by reaction temperature. It was also confirmed that crystalline BN formed under process conditions of higher than 1400 ℃.

Prediction of Retained Austenite Fraction in Quenching-and-Partitioning (Q&P) Steels Using the Gibbs Energy Balance Approach

Seong Hoon Kim,Ji Hoon Kim,Jae Hoon Lee,Dong‑Woo Suh,Jae Sang Lee 대한금속·재료학회 2022 METALS AND MATERIALS International Vol.28 No.9

Prediction of retained austenite fraction is quite important in designing advanced high strength steels since retained austeniteis the source of transformation-induced plasticity. The present study investigates the phase constitution of a medium-carbonQ&P steel by comparing various approaches to the transformation stasis of bainitic ferrite and applying them to the partitioningprocess. Among them, the modified GEB approach gave the best agreement with the experimental observation, includingthe effects of heat-treatment condition and chemical composition on phase constitution. This indicates phase transformationduring partitioning can be effectively described by the physics of Gibbs energy balance approach.

소아에서 발생한 골수이형성 증후군 2례

홍성진,윤석중,김성우,조형구,오명호,김기혁,이인성 건국대학교 의과학연구소 1996 건국의과학학술지 Vol.5 No.-

Myelodysplastic syndrome(MDS) is a group of acquired conditions characterized by progressive bone marrow failure associated with normocellular or hypercellular bone marrow that cannot be attributed to nutritional deficiency, chronic infection, or other chronic systemic illness, and cannot be reversed by the successful treatment of those conditions. Whereas the cases of secondary MDS occur at all ages, primary MDS is essentially a disease of elderly, though no age group is exempt and predomonant in men. The MDS is fundamentally clonal disorders at the level of the haemopoietic totipotent stem cell. Clinically, they are characterized by varing degrees of peripheral cytopenia(s) with morphological and functional abnormalities of blood elements. We have experienced two unrelated pediatric cases, who showed pancytopenia on admission and the characteristic marrow findings of MDS. The first case, a 12 months-old girl, showed increased reticulin with abnormal localization of immature precursor cells(ALIP) in her bone marrow, in addition to dysplastic features such as bi-and multi-nucleation of late normoblasts and internuclear bridging. She also showed 22% of blasts in her bone marrow cells thus classified in the category of RAEB-t after FAB classification. Also found were a chromosomal abnormality namely 46 XX t(14q21q), which was an unusual one. Her family brought her home and, 4 month later, she deceased. The second case, a 12 year-old boy, showed pancytopenia with Pseudo-Pelger-Huet anomaly in neutrophils but no blasts in the peripheral blood. Bone marrow of this case also showed the picture of dyserythropoiesis with binuclearity, internuclear bridging, nuclear fragments, multinuclearity of late normoblasts, in addition to megaloblastoid change in the normoblasts and increased mitosis in granulocytic series. No chromosomal abnormality was found. Classified as RA after FAB classification of MDS. Showed good response to conservative management for anemia for more than one year.

좌심방 석회화와 관련된 반복된 좌심방 혈전 1예

김성훈,우성용,오유경,정우백,임철현,신재원,박철수,윤호중,정욱성,홍순조 대한순환기학회 2004 Korean Circulation Journal Vol.34 No.3

폐산과 폐알칼리를 이용한 폐지류의 전처리

진양오,윤철종,우성훈,최성우,김익성,박승조 동아대학교 환경문제연구소 1999 硏究報告 Vol.22 No.1

The objective of this study were to treat waste paper with waste acid and alkali so to enhance maturity of the wastes. The sample was office paper and news paper which ratio was 1:1 and the reagents for pre-treatment were sulfuric acid and sodium hydroxide for waste acid and alkali. The maturity indices were taken volatile solid. cation exchange capacity, and gas production variation. The pre-treatment method was to dip the sample in the reagent according to time, concentration, and dosage. The methods of treatment were to dip the wastes in leachate and to landfill in soil. The result of this study were as follow. When waste paper was treated by acid and alkali, the proper treatment condition was 24hours and 0.1 normality of acid and alkali. The pre-treated samples with acid and alkali such as RSN and RSH were more effective in maturity than non-treated sample such as RS. The post-treated sample such as RSL, RSNL, and RSHL was more effective than nonpost-treated sample such as RS, RSN, and RSH.

축산분뇨중의 암모니아성 질소 제거

진양오,최성우,김성우,김익성,신남철,박승조 동아대학교 환경문제연구소 1999 硏究報告 Vol.22 No.2

The purpose of thus study were to investigate the proper conditions of struvite formation in synthetic wastewater and then to apply these conditions to effluent of anaerobic digester of livestock wastewater The conditions of struvite formation had been studied by many researchers. But a little conditions were different among them. Especially, according to suspended solid variation in livestock wastewater was investigated by few researchers. In experiment of synthetic wastewater, the proper conditions of struvite formation were pH 105, l50rpm of mixing rate, 10 minutes of reaction time, and 20 minutes of precipitation time. At same time, the ammonia nitrogen removal rates were about 99.7%, 95.5%, and 96% of synthetic wastewater, raw wastewater, and effluent of anaerobic digester of livestock wastewater at molar ratio of 2(Mg):l(N)2(P) respectively. The larger factor of NH₄/SS constant was, the more effective the removal rate of ammonium nitrogen, SS was, but the less effective COD_(cr), and TOC was. By using XRD analysis, the most certain compound in precipitate of synthetic wastewater was struvite.

메탈라스와 와이어메쉬로 횡구속된 철근 콘크리트 기둥의 내력 및 연성에 관한 연구

김병철,이우진,정덕우,윤승조,김성수,한천구 대한건축학회 2003 대한건축학회 학술발표대회 논문집 - 계획계/구조계 Vol.23 No.1(구조계)

Generally, transverse steel in reinforced concrete column serves the three-fold function of confining the compressed concrete, preventing lateral buckling of the longitudinal reinforcing steel, and acting as shear reinforcement. However, the amount of confining steel required in the form of rectangular hoops is still argument. This paper summarizes the results of an experimental program where 10 short columns with compressive strength 21MPa are designed with variable lateral confinements such as Metal Lath and Wire Mesh were tested under monotonic axial compression to failure. The columns were 300mm square and 750mm high. The purpose of this study is to investigate the ductility and strength of columns with variable lateral confinement. Test results indicate that specimen confined by metal lath and hoop, and wire mesh and hoop show 1.89 times ductility than NO.I specimen using hoop only. However, effect of lateral confinement by metal lath and wire mesh is how or same than NO.I specimen in maximum strength.

서울의 Penicillinase Producing Neisseria gonorrhoeae 발생빈도(1998)

김재홍,김준호,반재용,이정우,황성주,정준규,정성태,강진문,조흔정,홍창의,정혜신,이한승,김이선,이봉길,이종호,선영우,한기덕,윤성필,이성훈,안종성,박석범,문승현,조항래,김형섭,류지호,황재영,박준홍,손상욱 한양대학교 의과대학 2001 한양의대 학술지 Vol.21 No.1

In recent years, gonorrhea has been pandemic and remains one of the most common STDs in the world, especially in developing countries. For the detection of a more effective therapeutic regimen and assessing the prevalence of Penicillinase Producing Neisseria gonorrhoeae(PPNG), we have been trying to study the patients who have visited the Venereal Disease Clinic of Choong-Ku Public Health Center in Seoul since 1980 by menas of the chromogenic cephalosporin method. In 1998, 93 strians of N. genorrhoeae were isolated, among which 60(64.5%) were PPNG. The prevalence of PPNG in Seoul, which had been decreased to 39% in 1996 after a peak of 74.3% in 1993, is increased to 64.5% in 1998.

생물전극 반응조를 이용한 영양물질 제거

김성완,윤철종,최성우,김성우,우성훈,신남철,박승조 동아대학교 환경문제연구소 1999 硏究報告 Vol.22 No.2

We have investigated a performance of bio-electrode reactor for removal of nutrient like a nitrogen, phosphorus and organic substrate. Lab scale of bio-electrode reactor was operated with synthetic and tannery wastewater. Iron bar and stainless steel used for anode and cathode respectively. In experiment with synthetic wastewater, we were able to obtain the optimal current density range of 2.4-40 mA/dm² after 48 hrs operating time. And in that experiment, about 70~73% of ammonia nitrogen and 54~64% of phosphorus were removed. In experiment with tannery wastewater at 2.4-4.0 mA/dm², the removal rate of ammonia nitrogen, phosphorus and organic substract were about 62-69%, 45~59% and beyond 79% respectively.

열공형과 비열공형 피질하 혈관성 치매에서 위험인자의 차이에 관한 비교 연구

배희준,정지향,유경호,나덕렬,김상윤,최경규,양동원,손의주,이상도,김재우,박경원,김응규,이재홍,박미영,한일우,함동석,최문성,하충건,최성혜,이애영,이병철,한설희 대한치매학회 2003 Dementia and Neurocognitive Disorders Vol.2 No.2

Backgrounds and Objectives: Vascular dementia is a group of dementing disoders arising from various stroke syndrome. Among these. subcortical ischemic vascular dementia (SIVD) is regarded as a relatively distinct clinical entity. However, MRI patterns of SIVD are not homogenous. In some patients, lacunes are dominant, and in others, subcortical white matter changes are. This study was designed to compare risk factor profiles between SIVD with and without multiple lacunes. Methods: We divided 47 subjects (22 males, mean age. 68 years) recruited from VADAPET (Multicenter Trial For Evaluation Of The Changes In the PET Images Of Subcortical Vascular Dementia Patient) study into two groups one with more than 5 lacunes in deep gray matter (lacune group) and the other with 5 or less(non-lacune group) Clinical characteristics and laboratory findings of two groups were compared. Results: Nineteen of 47 patients (40%) belonged to the lacune group. The lacune and non-lacune groups d d not differ in the following variables: age, hypertension, diabetes mellitus, hyperlipidemia heart disease, history of stroke or TIA, history of trauma or major surgery, family history of hypertension stroke, or dementia, age at diagnosis of dementia, body mass index, white blood cell count, ESR, CRP, fibrinogen, hemoglobin A1C, total cholesterol. LDL cholesterol creatinine, proteinuria, glucosuria, and microhematuria. However, male sex, smoking alcohol. hemoglobin, and HDL cholesterol were possibly associated more with lacune group SIVD than with non-lacune group (p<0 1) Multivariate analyses revealed that smoking, hemoglobin, and HDL cholesterol were independent predictors of SIVD with multiple lacunes Conclusion: Our study suggests that SIVD with multiple lacunes may be significantly different in smoking habits hemoglobin, and HDL cholesterol from SIVD without multiple lacunes.