대기중의 습도에 따른 탄소강의 마모와 마찰

오흥국,연규현,김태훈 韓國工作機械學會 2000 한국생산제조학회지 Vol.9 No.3

The atmospheric humidity is varied between 30% and 90% with season in Korea. Thus the influence of humidity on the behavior of wear is important to predict the wear for tools and dies. This paper presents the influence of atmospheric humidity on the wear of carbon steels for the un-lubricated pin-on-disk sliding contact. It was found that the severe wear is dominant at a low humidity and the mild wear is strongly related with the carbon concentration of the steel at a high humidity in this study. The experiments were caned out in a chamber where the humidity was accurately maintained by humidifier. To investigate the relationship, three different carbon steels such as 1020, 1041, and 1045 steels were used.

소수계 유역 인공습지에서 식생 밀도 차이에 따른 영양염류 제거효율

고지연,강항원,이재생,김춘송,Sakadevan,K.,Bavor, H. J. 한국환경농학회 2003 한국환경농학회지 Vol.22 No.4

호주 시드니 인근 도·농 복합 소도시로부터 발생하는 비점오염원을 처리하기 위하여 설치된 Plumpton park와 Woodcroft park 인공습지의 처리효율을 살펴본 결과, 수생식물의 밀도가 증가하고 식생이 안정된 Plumpton park 인공습지에서 T-P의 26.2%, T-N의 38.3%, 식생분포가 안정적이지 않은 Woodcroft park에서 14.0%와 20.2%가 각각 제거됨으로서 식물체 근권 미생물에 의한 T-P 및 T-N의 제거 효율이 상당히 큼을 알 수 있었다. 또한 T-N와 T-P에 비하여 NH₄-N, NO₃-N, PO₄^(-3)의 제거율이 높았던 것은 무기태 형태의 영양염류가 식물 및 미생물에 더 쉽게 이용되었기 때문으로 생각된다. 이상의 결과로 볼 때 인공습지에서 식물체와 근권 주위 미생물에 의한 염류제거는 인공습지가 설치한지 오래되었을 때도 효과적이었고, 또한 인공습지는 무기태 영양염류의 제거효율이 더욱 높았으므로 무기화학비료 등의 용탈이 일어나기 쉬운 농경지 비점오염원으로부터 발생하는 수질오염의 개선에 이용할 수 있는 경제적이고도 효율적인 system으로 고려되었다. This study was conducted to evaluate effects of 2 constructed wetlands with different vegetation states (Plumpton park wetland and Woodcroft park wetland) for reducing non-point source pollution from small watershed consisted of residential and agricultural area in suburban district of Sydney, Australia. The total nitrogen and phosphate removal efficiency of Plumpton park constructed wetland, composed of stable and dense vegetation, were 38.3% and 26.2% and Woodcroft park constructed wetland having still poor vegetation due to the short time to settle down transplanted plants after construction, showed relatively low removal efficiency of 20.2% and 14.0%. The removal efficiency of inorganic nutrients such as NH₄-N, NO₃-N, PO₄^(-3) were higher than total nitrogen and phosphate because plants and microorganisms in rhizosphere of constructed wetlands took up inorganic nutrients shortly. According to the type of wetland inflow, the nutrients removal efficiency of storm water flow was lower than base flow.

Ω_n의 面上에서의 最小 퍼머넨트

辛恒均,崔兄模,李光淵 又石大學校 1994 論文集 Vol.16 No.-

퍼머넨트 이론에 있어서 가장 유명한 문제중의 하나였던 반 데르 배르덴의 추측이 해결되어 Ω의 여러 가지 면상에서의 최소 퍼머넨트를 결정하는 문제에 많은 관심이 집중되어왔다. 그 결과 Knopp과 Sinkhorn, Friedland, Brualdi 특정한 면상에서의 최소 퍼머넨트를 결정하였다. 본 논문에서는 두 개의 부분 영행렬을 가지는 Ω의 면상에서의 최소 퍼머넨트를 결정하는 문제에 대하여 고찰하려고 한다.

강재의 단축인장 시험과 마모와의 관계

오흥국,연규현,김태훈 韓國工作機械學會 2000 한국생산제조학회지 Vol.9 No.4

The reorientations of the atoms by frictional shear deformation at the surface induce cracks at the boundary of the grain. The cracks grow and propagate in regions where the hydrostatic component of stress is least com-pressive because the compressive component restores the cracks by three-dimensional crystallizing π-bondings. The materials, with Luder's band have very small amount of wear at the initial state. It suggests that initial frictional shear deformation be consumed to the formation of the Luder's band. The average wear amounts of the materials increase very steeply as the ø_u, the stress-strain ratio at the ultimate point, decreases.

6세 아동을 위한 파노라마방사선사진 상층의 연구

김상연,최항문,한진우,이설미 대한구강악안면방사선학회 2004 Imaging Science in Dentistry Vol.34 No.2

Purpose : To make a focal trough (image layer) for an average maxillary dental arch of 6-year-old korean in panoramic radiography. Materials and Methods : Phantom for the maxillary dental arch was designed using intercanine width, intermolar width, tooth size, and interdental spacing to record the data of 6-year-old child. The characteristics of pre-corrected panoramic machine (for adult) was evaluated using the phantom, resolution test pattern for margin of the image layer, and metal ball for the center of the image layer. Panoramic image layer of the child was developed by means of decreasing the speed of film-cassette and positioning the phantom backwards, and then the characteristics of post-corrected panoramic machine (for child) were reevaluated. Results : At post-corrected panoramic image layer, beam projection angles at all interdental areas increased for about 2.6-3.8.., the position of the image layer was shifted toward the rotation center for about 2.5 mm at the deciduous central incisior area. The width of image layer decreased at all areas. Conclusion : Increased beam projection angle will reduce the disadvantage of tooth overlap, and the same form between the center of the image layer and dental arch will improve image resolution.

정신장애인의 재활의 위한 사회기술훈련의 효과성에 관한 연구

황태연,손덕순,백형의,박종원,김지현,이경화 용인정신의학연구소 1999 용인정신의학보 Vol.6 No.2

보릿짚의 수분함량 및 수확시기가 소각시 대기오염물질 발생에 미치는 영향

고지연,강항원,이재생,김춘송,박성태,김복진 한국환경농학회 2004 한국환경농학회지 Vol.23 No.2

영남지방 벼-보리 이모작답에서 가장 널리 시행되고 있는 보릿짚 처리방법인 소각이 대기환경에 미치는 영향을 소각시 발생하는 온난화가스, 대기오염가스 및 분진발생량을 중심으로 살펴보았다. 보릿짚 소각시 온난화가스 발생량은 CO₂376.8, CH₄ 1.56, N₂O 0.05 kg/10a 로서 CO₂의 발생량이 가장 많았으며, 대기 오염가스 중에는 유기물의 불완전 연소시 배출되는 CO발생량이 28.8 kg/10a로서 가장 많았다. 그 외 SO₂ H₂S, NH₃, NO등의 질소 및 황 함유 유해가스도 소량 발생되었고 발생된 PM 10 분진의 대부분은 인체에 미치는 영향이 PM 10보다 큰 PM 2.5로 이루어져 있었다. 또한 수확시기가 빠르거나 수분함량이 높은 보릿짚일수록 온난화가스 및 대기오염 가스의 발생량이 증가하고 소각 연기내 PM 10 분진중 PM 2.5의 미세분진 비중이 높았다. 수확적기로 알려진 출수 40일 이후의 보릿짚은 출수 후 40일된 보릿짚 소각시 발생하는 대기오염가스 발생량과 큰 차이가 없었다. This study was carried out to determine impacts of burning of barley straw produced from rice-barley double cropping paddy field on air quality by investigating emissions of greenhouse gases (CO₂, CH₄ and N₂O), air pollution gases (CO, SO₂, H₂S, NH₃ and NO) and particulate matters (PM 10 and PM 2.5). When the barley straw at a rate of 4.5 t/ha was burned at open status, the emitted GHGs amounts were CO₂ 376.8 kg/10a, CH₄ 1.56 and N₂O 0.06. The amount of CO emission was the largest among air pollution gases. These results showed that the range of 45~55% of total C in barley straw was emitted as CO₂-C, followed by CO-C (6.4~5.9%) and CH₄-C (0.5~0.7%). As far as moisture content in barley straw is concerned, the higher moisture content that the barley straw contains, the larger amount of air pollution gases and the higher portion of PM 2.5 in PM 10 were emitted when it burned. In case of harvesting time of barley straw, emission amounts of greenhouse, air pollution gases and PM 2.5 portion in PM 10 had tendency to increase when earlier harvested barley straw was burned.

數學敎育의 現況分析과 改善方案 (Ⅱ) : 中·高校 數學科 運營과 敎師 現況分析 Analysis of administrations and teachers of today's math. department in the middle and high schools

林在圭,奇宇恒,金演哲,金正遠 慶北大學校 師範大學 1981 敎育硏究誌 Vol.23 No.-

Owing to the curriculum's revision of primary and high school in the beginning of 1970, several elementary concepts of modern mathematics were introduced as new teaching contents. So the efficient ways to reeducate the present teachers and to publish a desirable textbook have been badly needed. In this paper, we investigate the present situations of administration and teachers of mathematics department in the city and rural area. On the basis of these results, we find out the better ways of mathematics education from the following points of view: 1. The general administrations of mathematics department. 2. The reeducation and education for mathematics teachers. 3. Mathematics textbooks. 4. Evaluations and tests.

근골격계 질환 예방을 위한 재생타이어 트레드 버핑작업 개선에 관한 연구

김재열,한재호,이연신,김항우,오성민,송경석 한국공작기계학회 2004 한국공작기계학회 춘계학술대회논문집 Vol.2004 No.-

As a part of environmental pollution prevention and resources recycling, the regeneration of waste tire has been largely contributed to national industry. But, the worker has been evaded this regeneration process by reason of the best mischievous process condition among 3D industries.So, the first, the process condition of regeneratingwaste tire was analyzed. The second, the equipment or system was developed for the improvement of working strength and environment. The last, researchers intend to solve these problems

중학교 가정과 '인간발달과 가족관계' 영역의 교육자료 (CD-Rom) 개발 및 현장 적용 연구 : 실천적 추론 수업을 중심으로

유태명,장혜경,유지연,김주연,김항아,김효순 한국 가정과 교육 학회 2000 한국가정과교육학회지 Vol.12 No.3

The purpose of this study is to develop lesson plans. teaching guide, and teaching materials applying practical reasoning teaching model in the area of 'human development and family relationship' in middle school home economics. The practical reasoning teaching model consists of five factors: Desired results, Awareness of context. Alternative approaches, Consequences of action, and Action. This study based on practical reasoning has following process: Curriculum development, Developing lesson plan. teaching material, and teaching guide. Experimental teaching and evaluation, Feedback, Production of CD-Rom. Teaching guide includes lesson Plan. workbook, multimedia materials and teaching resources, Especially teaching guide in CD-Rom can be used effectively in the actual teaching. In the classroom, this teaching model accomplished active and interesting Participation of teachers and students. It is proposed that practical reasoning teaching model should be applied to other areas of home economics. In addition, various teaching materials based on Practical reasoning need to be developed.