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Change of plaque removal ability by worn toothbrush
이학철,양병근,이철우,이용무,류인철,정종평,한수부,Lee, Hak-Churl,Yang, Byung-Kun,Lee, Chul-Woo,Lee, Yong-Moo,Rhyu, In-Chul,Chung, Chong-Pyung,Han, Soo-Boo The Korean Academy of Periodontoloy 2004 Journal of Periodontal & Implant Science Vol.34 No.1
연구 목적: 3개월 간의 잇솔질에 따른 칫솔의 마모의 정도와 양상을 관찰하고, 이를 이용한 잇솔질 시의 치태 제거능력의 변화를 평가하여 일반적으로 권장되고 있는 3개월 주기의 칫솔 교체 주기의 근거를 실제 임상적으로 확인해보고자 하였다. 연구방법: 치주적으로 건강한 치과 대학생 52명을 대상으로 설문지를 통해 잇솔질 습관을 조사하고, 치석제거술을 시행하고 실험기간 동안 동일한 칫솔과 치약을 사용하게 하였다. 1주일 후와 2달과 3달째에 구강 내를 erythrosine으로 염색한 후 6개의 Ramfjord 치아의 plaque score를 측정하고, 3달 동안 사용한 칫솔을 수거하여 brushing surface area의 면적으로 마모도를 평가하였다. 결과: 6명이 탈락하였고 전체 부위의 plaque score는 1주 때와 비교하여 2,3 개월의 값이 통계학적으로 유의한 차이가 없었으나, 치간 부위의 plaque score는 3개월의 plaque score와 상관관계는 약하였다. 교체 주기, 잇솔질 횟수, 시간 등의 잇솔질 습관과 마모도의 연관성도 없었지만, 잇솔질 시간과 3개월째의 plaque score의 상관관계는 유의성 있는 결과를 보였다. 결론: 3개월 동안 사용한 칫솔의 치간 부위 치태제거 능력은 감소하였으며, 이의 임상적 영향에 대한 장기간의 연구가 필요하겠다.
이학철,한승민,설양조,이철우,엄흥식,장범석,정종평,한수부,Lee, Hak-Churl,Han, Seoung-Min,Seol, Yang-Jo,Lee, Chul-Woo,Um, Heung-Sik,Chang, Beom-Suk,Chung, Chong-Pyoung,Han, Soo-Boo 대한치주과학회 1999 Journal of Periodontal & Implant Science Vol.29 No.3
The purpose of this 6-months study was to compare the clinical and radiographic outcomes following guided tissue regeneration treating human mandibular Class II furcation defects with a bioabsorbable BioMesh barrier(test treatment) or a nonabsorbable ePTFE barrier(control treatment). Fourteen defects in 14 patients(mean age 44 years) were treated with BioMesh barriers and ten defects in 10 patients(mean age 48 years) with ePTFE barriers. After initial therapy, a GTR procedure was done. Following flap elevation, root planing, and removal of granulation tissue, each device was adjusted to cover the furcation defect. The flaps were repositioned and sutured to complete coverage of the barriers. A second surgical procedure was performed at control sites after 4 to 6 weeks to remove the nonresorbable barrier. Radiographic and clinical examinations(plaque index, gingival index, tooth mobility, gingival margin position, pocket depth, clinical attachment level) were carried out under standardized conditions immediately before and 6 months after surgery. Furthermore, digital subtraction radiography was carried out. All areas healed uneventfully. Surgical treatment resulted in clinically and statistically equivalent changes when comparisons were made between test and control treatments. Changes in plaque index were 0.7 for test and 0.4 for control treatments; changes in gingival index were 0.9 and 0.5. In both group gingival margin position and pocket depth reduction was 1.0mm and 3.0mm; clinical attachment level gain was 1.9mm. There were no changes in tooth mobility and the bone in radiographic evaluation. No significant(p${\leq }$0.05) difference between the two membranes could be detected with regard to plaque index, gingival index, gingival margin position, pocket depth, and clinical attachment level. In conclusion, a bioabsorbable BioMesh membrane is effective in human mandibular Class II furcation defects and a longer period study is needed to fully evaluate the outcomes.
압탕 최소화를 위한 터보차저하우징의 융합 S/W 응용 제조기술 및 실험적 검증
이학철 ( Hak-chul Lee ),서판기 ( Pan-ki Seo ),진철규 ( Chul-kyu Jin ),서형윤 ( Seo-hyung Yoon ),강충길 ( Chung-gil Kang ) 한국주조공학회 2017 한국주조공학회지 Vol.37 No.1
The purpose of this study is to increase the part recovery rate (to more than 70%) during the casting of a ductile cast iron turbo charger housing using a heater around the riser. Before creating a casting mold, various runner and riser systems were designed and analyzed with a casting simulation analysis tool. The design variables were the heater temperature, top insulation, riser location, riser diameter and the riser shape. During the feeding from the riser to the part, the reverse model was better than the forward model. When heating the riser (above 600 ℃), solidification of the riser was delayed and the feeding effect was suitable compared to that without heating. At a higher heating temperature, less solidification shrinkage and porosity were noted inside the part. On the basis of a casting simulation, eight molds were fabricated and casting experiments were conducted. According to the experimental conditions, external and internal defects were analyzed and mechanical properties were tested. The ultimate tensile strength and elongation outcome were correspondingly more than 540MPa and 5% after a heat treatment. In addition, a maximum part recovery rate of 86% was achieved in this study.
이학철(Hak-Chul Lee),김희철(Hee-Chul Kim),이상호(Sang-Ho Lee) 한국정보과학회 1995 한국정보과학회 학술발표논문집 Vol.22 No.2A
시각화되어진 프로그램은 문자 기반의 프로그램보다 많은 양의 정보를 효율적으로 제공해 줄 수 있다. 프로그램을 시각화시키기 위해 가장 많이 사용되는 방법으로는 함수 호출 방법(annotating 방법)이 있다. 이 방법은 교육자가 자신이 프로그램에서 나타내고자 하는 바를 자유롭게 표현할 수 있는 장점이 있으나 저 수준의 그래픽 처리 등의 많은 노력을 필요로 한다. 본 논문에서 제안하는 프로그램 시각화 시스템은 트리 알고리즘들 중에서 시각화 요소로 발생 가능한 프리미티브들을 선정하므로 써 함수 호출 방식을 이용한 시각화된 프로그램을 쉽게 만들 수 있게 한다.
이학철(Hak Churl Lee),류인철(In Chul Rhyu) 대한치과의사협회 2010 대한치과의사협회지 Vol.48 No.2
True vertical root fracture (VRF) in nonendodontically treated teeth confined to the root surface (fatigue root fracture; FRF) is apparently uncommon, the few documented reports being Chinese. The aim of this study is to analyze the cases of a fatigue root fracture and to find out the characteristic features of teeth with a FRF. A total of 21 consecutive cases of fatigue root fracture occurring in 16 patients were reviewed. In terms of the occlusion, the presence of restorations, the location, the age and gender, each tooth and patient were analyzed. The prevalent age was in those over 50 years of age (75%) and FRFs were more frequent in male patients (69%). Fatigue root fractures occurred most frequently in the mandibular molars (61.9%; 42.9% in first molar, 19% in second molar). Fatigue root fractures were observed most frequently in the teeth with no restorations (85.7%) and in the patients with occlusal problems (94%). FRFs seem to occur frequently and may represent an undiagnosed clinical entity deserving of our attention.
양웅모,김향미,장문석,박완수,김원남,김산웅,최동기,이학철,김윤경,박성규,Yang, Woong-Mo,Kim, Hyang-Mi,Chang, Mun-Seog,Park, Wan-Su,Kim, Won-Nam,Kim, San-Woong,Choi, Dong-Gi,Lee, Hak-Chul,Kim, Yun-Kyung,Park, Seong-Kyu 대한한의학방제학회 2006 大韓韓醫學方劑學會誌 Vol.14 No.2
The natural plants were screened for new cosmetic materials. Many parts of Nelumbo nucifera has been investigated for anti-wrinkling and anti-furrowing effects. The leaves. flowers and stamens of Nelumbo nucifera were extracted with ethanol or distilled water. The effects of cell viability and $H_2O_2-induced$ cytotoxicity were studied on CCD-986sk human fibroblast cell line by MTT assay. We measured various effects related to skin such as the synthesis of MMP-1 and type I procollagen. The ethanol extract of Nelumbo nucifera leaves (ENL) at concentrations of 30 ${\mu}g/ml$ showed maximum cell viability on CCD-986sk cells by 129.70%. and $H_2O_2-induced$ cytotoxicity was blocked by ENL (5. 10. 20. 30. and 40 ${\mu}g/ml$) concentration-dependently. The synthesis of MMP-1 and type I procollagen were positive in ENL. These results suggest that ENL has anti-oxidant and anti-furrowing effects.