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오늘 본 자료
이창우,서준표,강영호,Lee. Changwoo,Seo. Junpyo,Kang. Youngho 한국방재학회 2013 한국방재학회논문집 Vol.13 No.6
본 연구는 조선시대 산사태 발생현황과 특성에 대해서 현시대와 비교 분석하였다. 본 연구에 활용된 역사기록서는 조선왕조실록, 승정원일기, 비변사등록으로 이들 역사기록서에서 산사태, 토석류, 낙석을 포함하는 기록들을 고찰하였다. 조선시대 산사태 발생 원인은 강우가 81%로 가장 높았고, 50년 단위연도별 발생비율은 호우빈도와 유사한 결과로 나타났다. 그리고 월별산사태 발생 피해비율은 8월(30.7%), 7월(22.9%) 9월(18.8%) 순으로 나타났다. 또한 지역별 산사태 발생 피해비율은 강원도(16.3%), 서울(14.4%), 경기도 (13.4%), 경상북도(11.4%), 경상남도(10.9%) 순으로 나타났다. 결론적으로 조선시대의 산사태 특징은 발생원인과 빈발하는 월이 현재와 유사하였다. 또한 지역에 따른 피해발생비율도 유사점은 있었으나, 도심지에서는 다소 차이가 나타났다. 이러한 결과는 미래의 산사태 연구방향 및 정책수립에 대한 기초자료로 활용될 것으로 판단된다. In this study, the characteristic and occurrence on landslide of Joseon Dynasty were analyzed in order to compare with those of the present. Using the historical records on the Annals of Joseon Dynasty(朝鮮王朝實錄). The daily records of royal secretariat of Joseon Dynasty(承政院日記) and Bibyeonsadeungnok(備邊司謄錄), the record of landslide, debris flow and rockfall of Joseon Dynasty was investigated. The major cause of landslide of Joseon Dynasty was rainfall that was occupied by 81%, the ratio of landslide occurrence per 50 years was similar to frequency of torrential rain for same period. The ratio of landslide damage by month was the highest in August(30.7%) and the next was the July(22.9%) and September(18.8%) in order. And the ratio of landslide damage by region was the highest in Kangwon province(16.3%) and the next was the Seoul city(14.4%), Gyeonggi(13.4%), Gyeongbuk(11.4%), Gyeongnam(10.9%) province in order. The result show that causes, occurrence period and the damage ratio by regional on landslide of Joseon Dynasty were similar to those of the present, but there was a little difference in the city area. These results will be helpful to predict landslide trend in the future and set up policy countermeasures for landslide.
Module Type 소형 폰 카메라 렌즈모듈 조립장치 개발
이창우(Changwoo Lee),송준엽(Junyeob Song),하태호(Taeho Ha),이재학(Jaehak Lee),김천호 한국생산제조학회 2010 한국공작기계학회 추계학술대회논문집 Vol.2010 No.-
Micro-factory has many advantages but few examples of the commercialization. Because productivity and yield are less considered in micro-factory research. The micro-factory must also ensure productivity and yield in order to be commercialized. In this study commercialization of assembly micro-factory for phone camera lens module is a main goal.
수막을 가지는 선형 젖음성 패턴 표면에서의 액적 거동 특성
이창우(Changwoo Lee),박진영(Jinyoung Park),조한동(Handong Cho),황운봉(Woonbong Hwang) Korean Society for Precision Engineering 2013 한국정밀공학회지 Vol.30 No.12
Herein the water film was introduced to the hydrophilic area on the line patterned surface to solve the contradiction caused by surface roughness (high different wettability has advantage to control the droplet but high roughness for that high wettability difference causes obstruction of droplet moving). Thus the droplet on the water film could not be hindered to line direction but restricted to orthogonal direction, effectively. In addition, droplet behaviors according to droplet volume and line thickness were studied. Droplet fell off the line with narrowing the interface between the droplet and the water film on the line. When the droplet fell off the line, the plate angle was designated as a critical plate angle and it used as an indicator of surface capability to control the droplet. As a result critical plate angle increases as droplet volume decreases and line thickness increases.
도로터널 환기설계시 적정 차량항력계수 결정에 관한 연구
이창우(Changwoo Lee),조홍률(Hongryul Cho),박홍채(Hongchae Park) 한국유체기계학회 2006 유체기계 연구개발 발표회 논문집 Vol.- No.-
Quantifying the drag forces exerted by vehicles is critical for road tunnel ventilation safety design due to the high ratios they account for. Vehicle-induced forces occupy as much as 32~100% of the total ventilation forces acting inside tunnel, while in safety design, drag forces is in the range of 28 to 65% of the mechanical pressure required for the emergency fan. The method adopted in local design guidelines for determining the drag coefficient does not take into account the effects of slip streaming despite of the recommendation by PIARC. This paper aims at analyzing the effects of slip streaming on drag coefficient by varying vehicle type, blockage ratio, inter-vehicle distance and relative air velocity. A total of 192 cases in 4 different target tunnels with 4 levels of service, 2 types of vehicle, 6 different relative air velocities were numerically studied with SOLVENT. Some of the significant results can be summarized as follows: (1) If the inter-vehicle distance is kept constant, drag coefficient remains almost constant with relative air velocity of 5.0~28.3㎧. (2) Effects of slip streaming become more prominent, as traffic density increases and inter-vehicle distance gets shorter. Reduction of drag coefficient reaches 23~39%. However, differences in reduction ratios are not significant among the different vehicle types . (3) In the case of heavy vehicles, reduction in drag coefficient due to decreasing inter-vehicle distance shows linear relationship, while the relationship is not statistically significant for small vehicles. (4) Drag coefficient of small vehicles noticeably increases with higher blockage ratio under the relative air velocity of 5.0~28.3㎧ and the blockage ratio of 1.8~3.6%. However, the trend in heavy vehicles is not consistent, as drag coefficient increases up to the blockage ratio of 7.% and unexpectedly decreases thereafter. (5) The drag coefficient suggested by current local guidelines must be interpreted as its upper limit, and the suggested method for coefficient derivation should be reappraised.
회전형 자동 Pitch 조정 Multi Picker 개발
이창우(Changwoo Lee),송준엽(Junyeob Song),하태호(Taeho Ha),이재학(Jaehak Lee) 한국생산제조학회 2009 한국공작기계학회 추계학술대회논문집 Vol.2009 No.-
Cellular phone camera lens is produced by plastic injection molding process. Plastic injection mold has the gate through that lens mold is filled by molten plastic. Mold gate destroys the lens symmetry so lens has other special quality according to the orientation. Multi picker that can control the pitch has been introduced for productivity elevation. But the multi picker can not control the rotation. In this paper multi picker for lens module assembly is designed to control lens orientation and the pitch simultaneously.