• 제목/요약/키워드: tent

검색결과 148건 처리시간 0.031초

자동차 변속기용 정밀 부품의 용접변형 감소화에 관한 연구 (A Study on the Mitigation of Welding Distortion of a Precision Component for Automobile Transmission)

  • 정회윤;김재웅;윤석철
    • Journal of Welding and Joining
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    • 제30권4호
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    • pp.31-37
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    • 2012
  • In recent years, a demand for precision-welding is increasing in wide industrial fields for getting a high quality welded structures. Although laser welding is commonly used for precision-welding, gas tungsten arc (GTA) welding is also attempted as a precision-welding due to the cost benefit. However, welding heat causes an uneven temperature distribution leading to welding deformation. Since it causes geometric errors and degrades product quality, welding distortion recently rises as an important issue in the field of automobile parts. To control welding deformation, it is needed to design in shapes that can maximize stiffness against deformation during welding; control the welding sequence; minimize heat input; and weld allowing reverse deformation; etc. Thus it is necessary to find the one, among such approaches, that can minimize the deformation range by mathematical analysis and understand how effective it would be when it is actually used in industrial fields. This study performs analyses by numerical calculations and experiments for the De-Tent Lever, one of transmission part that requires precision the most among automobile parts, as the subject of experiment. Decrease in welding deformation is required for this part, since there is currently a trouble in guaranteeing precision due to angular deformation by welding between boss and plate. Finally the ways to minimize welding deformation has been suggested in this study through analyses on it.

경량 연자성 소재의 군 시설물 적용 시 방사선 차폐효과 분석 (Analysis of Radiation Shielding Effect of Soft Magnetic Material applied to Military Facility)

  • 이상규;이상민;최경준;이병학
    • 한국방사선학회논문지
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    • 제15권2호
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    • pp.191-199
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    • 2021
  • 본 연구의 목적은 경량 연자성 소재의 방사선 차폐 효과를 분석하여 군사시설에 대한 적용 가능성을 확인하는 것이다. 연자성 물질은 EMP 차폐에 효과적인 것으로 알려져 있다. 이 물질이 방사선 차폐에도 효과적이라면 군 방호에 효과적으로 적용이 가능할 것으로 예상된다. 이에 본 연구에서는 감마선 차폐 효과를 확인하기 위해 Cs-137 및 Co-60 선원을 사용하여 실험을 수행하였으며, 중성자 차폐 효과를 평가하기 위해 Monte Carlo N-Particle (MCNP) 모델링을 적용하였다. 그 결과 연자성 소재의 두께가 증가함에 따라 감마선과 중성자의 선형 감쇠 법칙에 의한 차폐성능이 향상됨을 확인할 수 있었다. 따라서 연자성 소재를 군사용 구조물 등에 적용할 경우에 방사선 차폐에 효과적이라는 것을 확인하였다.

혼돈신호를 이용한 IoT의 MQTT 보안 프로토콜 설계 (IoT MQTT Security Protocol Design Using Chaotic Signals)

  • 임거수
    • 한국정보전자통신기술학회논문지
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    • 제11권6호
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    • pp.778-783
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    • 2018
  • 정보통신과 산업기술의 급속한 발전으로 인간과 모든 프로그램 그리고 사물들이 인터넷을 통해 연결되는 초연결사회(hyper-connected society)가 구현되고 있다. 초연결사회를 구현하기 위한 정보의 수집은 사물과 사물 그리고 사물과 인간을 연결하는 사물인터넷(IoT: Internet of Thing)이 그 역할을 담당하고 있다. (MQTT: Message Queuing Telemetry Transport)는 이런 사물인터넷의 제약된 통신환경에 최적화되어 개발된 푸시 기술(push technology) 기반의 경량 메시지 전송 프로토콜이다. 초연결사회를 지향하면서 IoT가 담고 있는 정보는 센서의 환경정보에서 이제는 사람의 질병과 건강관리까지 담당하는 광범위한 정보가 되었다. 이런 MQTT에 대한 보안 문제는 환경정보 유출뿐만 아니라 개인의 정보 침해에까지 이르게 되었다. 우리는 이런 MQTT의 보안의 문제점을 해결하기 위해 혼돈계의 초기치 민감성, 유사 난수성을 무결성과 기밀성에 적용하여 새로운 보안 MQTT통신방법을 설계하였다. 우리가 설계한 혼돈계를 이용한 암호화 방법은 구조가 간단하고 계산량이 적기 때문에 IoT와 같은 제한된 통신환경에 적합한 통신방법이라고 생각된다.

개방 공간에서 발생하는 수소-공기 혼합 가스 폭연에 대한 실험적/해석적 연구 (Experimental and Analytical Study on Hydrogen-air Deflagrations in Open Atmosphere)

  • 김양균;박병직
    • 한국안전학회지
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    • 제36권1호
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    • pp.64-71
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    • 2021
  • Experimental and analytical investigations are performed to explore the explosion characteristics of a hydrogen-air mixture in open atmosphere. A hydrogen-air mixture tent of total volume of 27 m3, with 40% hydrogen volume, is used to observe overpressure at a distance from the ignition source. Vapor cloud explosion analyses are performed using the TNO multi-energy model and Baker-Strehlow-Tang model. The results of these analyses are compared with experiment done from this study and references. The experimental results with and without obstacles indicate that the overpressure values measured at a distance of 4.5-21.5 m from the ignition source are about 9.4-3.6 kPa and 6.5-2 kPa, respectively. This implies that the overpressure with obstacles is approximately 1.7 times greater than that without obstacles. Analytical observation indicates that the results obtained with the Baker-Strehlow-Tang model with Mf = 0.2-0.35 are in good agreement with those of most of the previous studies, including that obtained from this study. Moreover, the TNO multi-energy model with a volume of 27 m3 well predicts the overpressure obtained from this study. Further studies should considered explosions in semi-confined spaces, which is more suitable for hydrogen refueling stations.

홉프의 재배환경과 개화후 일수에 따른 $\alpha$-acid 함량 변화 (Influence of Days after Flowering and Cultural Environments on Changes of Alpha-Acid Content in Hops (Humulus lupulus L.))

  • 박경열;이동우;민인기
    • 한국작물학회지
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    • 제32권1호
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    • pp.97-102
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    • 1987
  • 홉프의 개화후 경과일수와 재배지 표고 및 연차간 기상 변화에 따른 $\alpha$-acid 함량의 변이를 구명하고 진행한 시험 결과를 요약하면 다음과 같다. 1. 홉프 $\alpha$-acid 함량은 개화후 50일경부터 70일경까지 최대에 달하였으며, 개화후 61일에 6.895%로써 최대치를 나타내었다. 2. 수확기에 따른 $\alpha$-acid 함량양은 표고가 낮은 130m이하에서는 수확기간에 미미한 변화를 나타내냈으나 그 이상의 표고에서는 8월 11일부터 15일경까지 수확한 것에서 타 수확기 보다 높았다. 3. $\alpha$-acid 함량이 가장 높은 표고는 190-260m이었고, 이보다 표고가 높거나 낮을수록 $\alpha$-acid 함량은 감소되었으며 표고 130m이하에서 가장 낮았다. 4. $\alpha$-acid 함량은 매년 정규분포를 나타내었으며, 동일 연도의 표고별 차이보다 동일 표고별 연차간 차이가 컸으며, 동일 연도내 표본간 CㆍV는 7.30~7.83%에 비하여 연차간 CㆍV는 19.26%로서 연차각 변이가 심하였다. 5. $\alpha$-acid 함량은 7월 하순의 최고기온과는 고도의 정상관, 평균기온과 일조시수와는 정상관, 강수양과는 부의 상관이 있었다. 6. 홉프의 생종화 수량과 $\alpha$-acid 함량은 유의한 정상관이 있었다.

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Indole-3-butyric acid(IBA) 침지처리에 의한 highbush blueberry 'Duke', 'Elizabeth', 'Elliot' (Vaccinium corymbosum L.)의 녹지삽목 발근 촉진 (Promoted rooting of softwood cuttings of highbush blueberry 'Duke', 'Elizabeth', 'Elliot' (Vaccinium corymbosum L.) as affected by indole-3-butyric acid(IBA) dipping treatment)

  • 강성구
    • 현장농수산연구지
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    • 제17권1호
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    • pp.145-155
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    • 2015
  • 간이 녹지삽목시설의 실용성과 발근촉진제 IBA의 발근촉진효과를 조사하기 위하여 북부 highbush blueberry 3품종 'Duke', 'Elizabeth', 'Elliot'를 공시하여 IBA 100ppm, 300ppm, 500ppm, 1,000ppm의 2시간 처리와 3,000ppm 20초 침지처리를 실시한 후 발근특성을 조사하였다. 분산분석에 의한 요인분석 결과, 발근율과 근계지수에 품종효과가 있었으며 발근율, 최대근장, 근계지수에서 IBA의 처리효과도 관찰되었다. 특히 근계지수에서 고도의 유의성 있는 처리효과가 있었다. 그러나 두 요인의 상호작용은 없었다. 무처리구에서 'Duke'의 발근율은 45%, 'Elizabeth'와 'Elliot'는 각각 90%와 85%로 품종간 차이가 있었으며 3품종 모두 고농도 20초 처리와 저농도 2시간 처리구에 의하여 발근이 촉진되었다. 그러나 무처리의 발근율이 낮았던 'Duke'의 발근촉진효과가 다른 두 품종에 비해 현저하였다.

Suggestions for E-Learning Based on Four Years of Cyber University Experience

  • LEE, Okhwa
    • Educational Technology International
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    • 제6권1호
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    • pp.41-63
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    • 2005
  • E-Learning is widely introduced with cyber universities in Korea from 2001 whencyber universities were first authorized by the Ministry of Education and Human Resource Development. E-learning amplified by cyber university gave a big impact in the campus based university which became the cause for the educational paradigm shift. The changes of status of cyber university shows important trend in college education which was analyzed by enrollment rate, types of cyber university, demography, and study areas. The enrollment rate of cyber universities is ever since 2001 and variety of study areas gives popularity to students. The demography of students is as expected older than traditional students. Female students at the cyber university outnumbered that at campus based university in Korea. For analyzing the trend of e-learning in Korea, there were studies twice in 2001 May-June from 213 faculty members and staff, 630 students and in 2004 May-June with 401 students. Most of e-learning students tent to spend less time yet, students feel more burden with e-learning. Professors tend to load more materials for the e-learning in 2001but in 2004 study, the difference no longer exists. Professors and students feel the academic achievement through e-learning is not as good as from the traditional classes. Difficulties for e-learning in 2001 were the lack of administrative information but in 2004, boring contents and lack of instructional strategies for e-learning. Technical problems still do exist but less serious. Suggestions for e-learning are blended learning, online students prefer video streaming with their own lecturer, new definition of instructor is needed, professional development for content development and online instruction is needed, success story of online learning should be encouraged, guidance for online students needed. The cyber university experiencegave a positive impact on the traditional universities such as rethinking the roles of universities, the quality control of classes, professional development, student oriented educational service of e-learning pedagogy.

크리핑 벤트그라스 훼어웨이에서 관수회수.예지물과 질소시비수준이 엽조직 및 토양 질소함유량에 미치는 효과 (A Three-year Study on the Leaf and Soil Nitrogen Contents Influenced by Irrigation Frequency, Clipping Return or Removal and Nitrogen Rate in a Creeping Bentgrass Fairway)

  • 김경남;로버트쉬어만
    • 아시안잔디학회지
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    • 제11권2호
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    • pp.105-115
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    • 1997
  • Responses of 'Penncross' creeping bentgrass turf to various fairway cultural practices are not well-established or supported by research results. This study was initiated to evaluate the effects of irrigation frequency, clipping return or removal, and nitrogen rate on leaf and soil nitrogen con-tent in the 'Penncross' creeping bentgrass (Agrostis palustris Huds.) turf. A 'Penncross' creeping bentgrass turf was established in 1988 on a Sharpsburg silty-clay loam (Typic Argiudoll). The experiment was conducted from 1989 to 1991 under nontraffic conditions. A split-split-plot experimental design was used. Daily or biweekly irrigation, clipping return or removal, and 5, 15, or 25 g N $m-^2$ $yr-^1$ were the main-, sub-, and sub-sub-plot treatments, respectively. Treatments were replicated 3 times in a randomized complete block design. The turf was mowed 4 times weekly at a l3 mm height of cut. Leaf tissue nitrogen content was analyzed twice in 1989 and three times in both 1990 and 1991. Leaf samples were collected from turfgrass plants in the treatment plots, dried immediately at 70˚C for 48 hours, and evaluated for total-N content, using the Kjeldahl method. Concurrently, six soil cores (18mm diam. by 200 mm depth) were collected, air dried, and analyzed for total-N content. Nitrogen analysis on the soil and leaf samples were made in the Soil and Plant Analyical Laboratory, at the University of Nebraska, Lincoln, USA. Data were analyzed as a split-split-plot with analysis of variance (ANOVA), using the General Linear Model procedures of the Statistical Analysis System. The nitrogen content of the leaf tissue is variable in creeping bentgrass fairway turf with clip-ping recycles, nitrogen application rate and time after establishment. Leaf tissue nitrogen content increased with clipping return and nitrogen rate. Plots treated with clipping return had 8% and 5% more nitrogen content in the leaf tissue in 1989 and 1990, respectively, as compared to plots treated with clipping removal. Plots applied with high-N level (25g N $m-^2$ $yr-^1$)had 10%, 17%, and 13% more nitrogen content in leaf tissue in 1989, 1990, and 1991, respectively, when compared with plots applied with low-N level (5g N $m-^2$ $yr-^1$). Overall observations during the study indicated that leaf tissue nitrogen content increased at any nitrogen rate with time after establishment. At the low-N level treatment (5g N $m-^2$ $yr-^1$ ), plots sampled in 1991 had 15% more leaf nitrogen content, as compared to plots sampled in 1989. Similar responses were also found from the high-N level treatment (25g N $m-^2$ $yr-^1$ ).Plots analyzed in 1991 were 18% higher than that of plots analyzed in 1989. No significant treatment effects were observed for soil nitrogen content over the first 3 years after establishment. Strategic management application is necessary for the golf course turf, depending on whether clippings return or not. Different approaches should be addressed to turf fertilization program from a standpoint of clipping recycles. It is recommended that regular analysis of the soil and leaf tissue of golf course turf must be made and fertilization program should be developed through the interpretation of its analytic data result. In golf courses where clippings are recycled, the fertilization program need to be adjusted, being 20% to 30% less nitrogen input over the clipping-removed areas. Key words: Agrostis palustris Huds., 'Penncross' creeping bentgrass fairway, Irrigation frequency, Clipping return, Nitrogen rate, Leaf nitrogen content, Soil nitrogen content.

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비닐하우스 이용 태양초 생산시 산광 재료가 상품 수량과 품질에 미치는 영향 (Effects of Diffused Light Materials on Marketable Yield and Quality of Sunlight Dried Red Pepper (Capsicum annuum L.) in Plastic Film House)

  • 이광재;송명규;김시동;남상영;이기열;김태중;김동억;윤정범;최규홍
    • 한국자원식물학회지
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    • 제27권1호
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    • pp.102-109
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    • 2014
  • 본 연구는 태양초 생산시 전처리와 산광 재료가 상품성과 건조 효율에 미치는 효과를 구명하기 위하여 실시하였다. 벌크, 하우스 밀폐, PE비닐밀봉 처리 등 전처리를 하였으며, 산광 재료로 대조구, 차광망 35%, 천막지, 백색부직포, 흑색부직포 등을 사용하였다. 벌크 후숙 처리구의 상품 수량이 300 g으로 가장 많았으며, 하우스 건조가 275 g이었으며, PE 밀봉 처리구가 112 g으로 가장 적었다. 적색도는 PE 밀봉 처리시 17.85로 가장 높았고 벌크 후숙 처리에서 가장 낮았으며, 각각의 처리 간에 유의성이 인정되었다. 고추의 수분 감모 속도는 대조구가 가장 빨랐으며, 차광망 처리구가 가장 늦었다. 상품 수량지수는 백색부직포가 대조구 100%에 비해 114%로 가장 높았다. 적색도는 흑색부직포와 천막지가 15.65로 다른 처리와 유의성을 나타냈다. 캡사이신 함량은 흑색부직포에서 $160mg{\cdot}100g^{-1}$로 가장 높았다. 비닐하우스 이용 태양초 생산시 비닐하우스 밀폐 전처리를 하고 백색부직포로 산광하면 대조구보다 건조기간은 2일 정도 지연되었으나 상품 수량은 14% 증가하였다. 본 실험에서 얻어진 결과는 태양초 생산 효율 증진뿐만 아니라 향후 연구에 도움이 되리라 기대된다.

윤초창(尹草窓)의 생애(生涯)와 초창결(草窓訣)에 관(關) 연구(硏究) (A Study on the life of Yoon Cho Chang(尹草窓) and Cho-Chang-Kyeul(草窓訣))

  • 김준태;윤창열
    • 대한한의학원전학회지
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    • 제6권
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    • pp.189-227
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    • 1993
  • I have studied life of Yoon-Dong-Li(尹東里), who applied Un-Ki(運氣) theory to medicine during Suk-Jong(肅宗) to Joong-Jo(正祖) in Yi-Dynasty and also studied his existing writings named ${\ll}$Cho-Chang-kyeol${\gg}$ (草窓訣). The referenced original work prints were based on 1980's print of Chung-Ku oriental medical society and National Central Library and The academy a korean studies possessed print. Studied with these books, I have concluded as follows. 1. Yoon-Dong-Li(尹東里) courtesy name is Ja-Mi(子美), pen name is Cho-Chang(草窓). He was born in 1705, Suk-Jong(肅宗) 31yrs, and died in 1784, Jeong-Jo(正祖) 8yrs in Yi-Dynasty. He had lineage of third-generationed-doctor and learned medicine from his uncle, Yoon-Woo-Kyo(尹雨敎). His father Yoon-Yi-Kyo(尹이敎) gaved him second influence. 2. Confucianal physician in Ming Dynasty You-Bu(劉溥) respected Ju-Ryeom-Kye(周溓溪), confucianist in Song-Dynasty and You-Bu(劉溥) does not removed grass in front of window (because in chinese, Cho-Charig(草窓) means grass in front of window), and named himself Cho-Chang(草窓). Yoon-Dong-Li(尹東里) followed this suit so called himself Cho-Chang (草窓). 3. The main contents of ${\ll}$Cho-Chang-Kyeol${\gg}$ (草窓訣), (運氣衍論) was written in 1725, when Yoon-Dong-Li(尹東里) was 21yrs old and printed in 1736. The other part of ${\ll}$Cho-Chang-Kyeol${\gg}$ (草窓訣), (用藥篇) was written in 1746. These two parts were not written in the satre time. The (運氣衍論) was written llyears earlier than (用藥). Two parts were combined another day and named (草窓訣). 4. Existing ${\ll}$Cho-Chang-Kyeol${\gg}$ (草窓訣) is transcribed printing with the con tent of "Five elements motion and the six kind of natural factors theory" (五運六氣設). Each edition is generally similar in content, but also has different points each other so naw we hardly finds a complete set of works. 5. ${\ll}$Cho-Chang-Kyeol${\gg}$ (草窓訣) is a first technical book which treats of Un-Ki(運氣) theory in korea. 6. The contents of (運氣衍論) of ${\ll}$Cho-Chang-Kyeol${\gg}$ (草窓訣) is mechanism of diease according to excess and insuffciency of five elements motion and six kinds of nalural faclors.and symploms and priscriptions, includes variated priscriptions. 7. Two parts in (運氣衍論) of ${\ll}$Cho-Chang-Kyeol${\gg}$ (草窓訣), 'Sang-tong' (相通) and 'Kak-Tong' (各通), threats of mochanisim of the disease according to five elements. with the principle of inter-promoting and inter-acting, in the change of ten heavenly stems and five elements motion. 8. In the (用藥篇) of ${\ll}$Cho-Chang-Kyeol${\gg}$ (草窓訣) describes priscription for clinical application according to Un-Ki(運氣) and also records about misuse of medicine. 9. In the ${\ll}$Cho-Chang-Kyeol${\gg}$ (草窓訣), most of priscription are common using one, which also found in ${\ll}$Dong-$\breve{U}$i-Bo-Garm${\gg}$ (東醫寶鑑) and there are few of priscriptions hy Yoon-Dong-Li(尹東里).

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