http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
- 中文 을 입력하시려면 zhongwen을 입력하시고 space를누르시면됩니다.
- 北京 을 입력하시려면 beijing을 입력하시고 space를 누르시면 됩니다.
RISS 인기검색어
- 검색키워드
- 저자 : 황효연(Hyo Yeon Hwang) (검색결과 5 건)
- 무료
- 기관 내 무료
- 유료
-
고압산소요법이 백서의 방사선 이하선염에 미치는 영향에 관한 실험적 연구
황효연(Hyo Yeon Hwang),윤중호(Jung Ho Yoon) 대한구강악안면외과학회 1999 대한구강악안면외과학회지 Vol.25 No.1
Main objectives of this study were to produce the experimental postirradiation sialadenitis and to observe the effects of hyperbaric oxygen therapy after the production of postirradiation sialadenitis in the unilateral parotid gland of white rats. To produce the experimental postirradiation sialadenitis, author attempted the various methods of irradiation such as 1000rad weekly for 5 weeks, or single dosage of 2000rad, 3000rad, 5000rad, but those attempts were futile due to the high mortality of experimental animals.(used 80 rats for pilot study) Finally author had to design fractional irradiation, that is, 1000rad per 2 weeks, total 5000rad for 8weeks in order to produce postirradiation sialadenitis. The occurrence of postirradiation sialadenitis was proved with serial salivary scan findings. Author used irradiated 100rats, dividing into the control(50) and experimental group (50) and rendered the hyperbaric oxygen therapy(2 hours/daily at 2.4ATM) on the experimental group for 6 weeks. The effect of hyperbaric oxygen therapy was examined by salivary scan findings and microscopic examination. The obtained results of this study were as follows: 1. The differences of salivary gland function between irradiated parotid glands(right) and nonirradiated parotid glands(left) showed the most remarkable changes at 32 weeks after total 5000rad irradiation. 2. In microscopic examination at 32 weeks after total 5000rad irradiation, irradiated parotid glands(right) showed severe degenerative changes of acinar cells, separations of lobules due to edema, severe intralobular fibrosis and connective tissue fibrosis. 3. After hyperbaric oxygen therapy for 4 weeks, the effect of hyperbaric oxygen therapy showed no distinctive differential findings between the control and the experimental group with salivary scan findings(P≥0.05), while the experimental group showed progressive intralobular edema, capillary proliferation, hyperemia in connective tissues and intralobular fibrosis in microscopic examination. 4. Tc99m uptake of the experimental group was raised after hyperbaric oxygen therapy for 6 weeks, and showed reduction of Tc99m uptake ratio between irradiated parotid gland and nonirradiated gland up to 8 to 10 weeks(P<0.05), while in the microscopic exemination the experimental group showed aggravated acinar cell degeneration, intercalated duct proliferation, connective tissues fibrosis. In this study, author speculated that though the hyperbaric oxygen therapy improved the capillary impairment, there was a tendency to increase the degenerative changes of parechyma of postirradiated parotid glands, thus the usage of the hyperbaric oxygen therapy should be considered carefully in the aspect of hazardous effect to the parotid parenchymal tissues.
-
-
아크릴산 단량체와 아지리딘 경화제 함량에 따른 점착제의 점착물성 변화
최환석(Hwan Seok Choi),황효연(Hyo Yeon Hwang),정선경(Sun Kyoung Jeoung),이승구(Seung Goo Lee),이기윤(Kee Yoon Lee) 한국고분자학회 2012 폴리머 Vol.36 No.1
관능성 단량체로서 acrylic acid(AA)를 사용하였고, 기본 단량체로서는 2-ethylhexyl acrylate(2-EHA)를 사용하여 용액중합의 방법으로 점착제를 합성하였다. 점착제의 점착물성 중에 AA와 경화제 함량에 따른 점착제의 표면에너지와 물성변화 연구를 조사하였다. 합성된 점착제의 구조는 FTIR을 통하여 확인하였고 점도와 분자량은 Brookfield 점도계와 GPC를 사용하여 각각 측정하였다. 분자량과 점도는 AA가 6 wt%까지는 함량증가에 따라 증가하였으며 6 wt% 이상에서는 감소하였다. 이러한 경향은 표면에너지 역시 AA 함량증가에 따라 COOH 그룹에 의한 극성 강화로 표면에너지는 증가하였다. 반면, 점착력은 분자량과 반비례 관계를 보였으며 AA 함량과 경화제 함량 증가에 따라 감소하는 경향을 나타내었다. Solution type pressure sensitive acrylic adhesives were synthesized from 2-ethylhexyl acrylate (2-EHA) as a base monomer and acrylic acid as a functional monomer. The surface energy and basic physical properties of synthesized PSA (pressure sensitive adhesives) were investigated as a function of contents of acrylic acid and crosslinking agent. The structures of adhesive were identified by FTIR. Viscosities and molecular weights of PSA were measured by a Brookfield viscometer and GPC, respectively. Consequently, molecular weight and viscosity increased as the contents of acrylic acid increased up to 6 wt% and then decreased at higher contents. Surface energy increased as the contents of acrylic acid increased owing to the increase of COOH groups, which yielded the enhancement of polarity of PSA. On the other hands, their peel strengths were inversely proportional to molecular weight and showed tendencies of decreasing as the contents of acrylic acid and crosslinking agent increased.
-
판상형 충전제의 함량과 배향에 따른 PP복합체의 열팽창계수 영향 연구
이기윤(Kee Yoon Lee),이용현(Yong Hyun Lee),정선경(Sun Kyoung Jeoung),황효연(Hyo Yeon Hwang),이승구(Seung Goo Lee) 한국고분자학회 2012 폴리머 Vol.36 No.3
두 가지의 종횡비(ρα=a1/a3 and ρβ=a1/a2)에 의해 특징지어진 3차원 타원체(a1 > a2 > a3)를 사용하여 polypropylene 복합체의 판상형 충전제 함량과 방향이 열팽창률에 미치는 영향에 대해 실험적인 연구를 수행하였다. 측정된 실험적인 값은 Lee와 그의 연구자들이 제안한 이론적인 모델에 의한 계산 값과 비교분석되었다. 판상형충전제로는 운모와 탈크가 사용되었다. 실험 결과로 운모의 경우 종횡비는 ρα= 13.5, ρβ= 1.8이 사용되 어, 20 wt% 함량일때 α11/αm는 약 0.56으로 감소하였으나, α33/αm는 오히려 1.018로 증가함을 보였다. 탈크의 경우의 종횡비는 ρα=3.7, ρβ= 1.4이었고 α11/αm는 0.63으로 감소하였다. 결국 운모와 탈크 모두 그 함량증가에 따라 종단방향과 횡단방향에서 열팽창률은 감소하였으나 수직방향에서는 초기 낮은 충전제 함량에서는 오히려 증가하는 경향을 보였다. Experimental study was performed regarding the effects of disc-like filler orientation and contents on the coefficient of thermal expansion (CTE) of polypropylene composites using the three dimensional ellipsoids (a1 > a2 > a3) analyzed by two aspect ratios(ρα=a1/a3 and ρβ=a1/a2). Measured data were compared with the theoretical approaches proposed by Lee et al. Mica and talc were useed as disk-like fillers in the composites. As experimental results, α11/αm decreased down to ca. 0.56 with mica content of 20 wt% and the aspect ratios, ρα=13.5, ρβ=1.8. However, α33/αm increased to more than 1. In the case of talc, α11/αm decreased to ca. 0.63 with 20 wt% and ρα=3.7, ρβ=1.4. Finally, the longitudinal CTEs (α11) of polypropylene composites decreased as filler contents increased, but normal CTE (α33) increased in the low filler contents like the theory.
-
ScienceON연관 검색어 추천
이 검색어로 많이 본 자료
활용도 높은 자료
