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우(牛) 하악골의 천공시 발생하는 마찰열에 관한 실험적 연구
황효연(Hou Yon Hwang),윤중호(Jung Ho Yoon) 대한구강악안면외과학회 1984 대한구강악안면외과학회지 Vol.10 No.2
The removal of cancellous and cortical bone in oral and maxillofacial surgery is frequently accomplished with burs. Heat generated from drilling is due to the friction and the fragmentation of particles of bone at the cutting edge of the drill. The frictional heat has serious consequences leading to hyperemia, fibrosis, osteocytic degeneration and increased osteoclastic-osteoblastic activity, dehydration, dessication, shrinkage, carbonization, and nercrosis. Various techniques applied to reduce or limit frictional heat arising from drilling included slow rotational speeds, intermittent drilling, sharp drilling instruments, external irrigation, internal irrigation with water or saline solution. This study was undertaken to compare frictional heat of the No. 6 round bur to the No. 702 fissure bur under the controlled condition, that is, 4800 rpm, drilling force of 1, 2, or 3㎏, external irrigation with 18℃ 0.9% saline solution, no irrigation, preparation of 5 ㎜ cavity in depth, temperature measurements at 1 ㎜ distance from the experimental cavity, using the bovine mandibles in vitro. The obtained results were as follows. 1. The lowest frictional heat was generated, when the No. 6 round bur was used with iirigation, with drilling force of 1 ㎏. 2. The effect of irrigation was evident, when the No. 6 round bur was used with irrigation, with drilling force of 1㎏ or 3 ㎏. but, unevident in drilling force of 2 ㎏. 3. The frictional heat was independent of the drilling force of 1㎏ or 2㎏, when the No. 702 fissure bur was used with irrigation. 4. There was no temperature variation between the No. 6 round bur and the No. 702 fissure bur, when cavity preparation was done with irrigation, drilling force of 2㎏.
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.
경골의 전방 피질골 피로 골절에 대한 저에너지 체외충격파 치료
김영범 ( Young Bum Kim ),가효연 ( Hyo Yun Ga ),황지혜 ( Ji Hye Hwang ) 대한스포츠의학회 2011 대한스포츠의학회지 Vol.29 No.2
Anterior cortex of the tibia is one of the intractable stress fracture sites ocurring in athletes, which are result of repetitive use damage that exceeds the intrinsic ability of the bone to repair itself. It is sometimes difficulty to repair the anterior cortical stress fracture, which result in delayed union or nonunion. Extracorporeal shock wave therapy (ESWT) can be an useful method in the management of stress fracture of the anterior cortex of the tibia. We present a case of an young athlete affected by chronic stress fractures of the anterior cortex of the tibia that received low energy ESWT. The clinical result was excellent and he was able to gradually return to sports activities.